Last October Jan Gerber was on a beach on a private island in the Seychelles when “a depression hit that had never hit me before. I’d be brushing my teeth in the morning and I’d feel the darkening coming on. I’d crawl to the floor and just lie there crying.

“My fiancée would find me half an hour later and have to get me to bed. It was the most beautiful place in the world, a boutique resort surrounded by a national park, but I had plunged into a dark ocean. I saw so clearly there is no meaning, there’s just pain, so why keep going?”

Gerber had plenty of experience of other people’s breakdowns, as the founder and chief executive of Paracelsus Recovery, the world’s most expensive — and exclusive — rehab clinic, costing clients about £100,000 a week.

This is where film stars, royalty, elite sportspeople, and CEOs check in suffering from burnout, depression and/or addiction. For them a white-walled psychiatric hospital simply will not do.

Yet the strain of building up this business brought Gerber, 43, to this point where he wanted to commit suicide, but lacked the energy to form or carry out a plan. “I wouldn’t have minded if a bus ran over me.”

The son of a Swiss psychiatrist father and nurse mother, Gerber studied accounting at the London School of Economics before becoming a management consultant and serial entrepreneur. The idea for an ultra-exclusive clinic was born after a friend of a friend, who was the boss of a listed company, needed discreet help for alcoholism. Gerber curated his treatment, sourcing him a butler and a yoga instructor.

“I realised there was a niche of very exposed, famous and ultra-wealthy people who couldn’t just walk into rehab or a clinic. Their family, or the public, or business partners might find out.”

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Gerber and his mother pioneered a fully holistic approach, with each client assigned a team of 15 to 20 people, including psychiatrists, nurses, masseuses, nutritionists and a live-in therapist. “If you really want to unearth all the factors that contribute to a problem and find bespoke treatments, you need to throw massive resources at it. That costs a lot.”

Paracelsus Recovery was founded 12 years ago, since when about 400 high-profile clients — mainly American, but many from the Middle East and Europe, have checked in to its three (the maximum number of clients treated at any one time) apartments on the shores of Lake Zurich, complete with a live-in therapist available 24/7 and personal chef. From there, they can walk discreetly — via the bins — the 30 seconds to the clinic, with sessions arranged so that no client ever sees another.

Its staff have become experts in understanding the issues that uniquely plague ultra-high-net-worth individuals — defined as people worth more than £37 million — with research showing that despite their financial cushions, people in that bracket are three to five times more likely than the average to suffer from a mental illness or substance abuse problem.

“These people live in a separate reality,” Gerber says. “They’re surrounded by people who daren’t say no, who want your money, who are affiliated with you for reasons other than being interested in you as a human being and that makes you very lonely.”

It’s a 40-minute drive from Zurich to the restored 150-year-old house — we were chauffeured here in a Bentley — which Gerber shares with his fiancée, Jil, and their adored retriever. Having shown us round the underground gym, with its sauna, steam room, Japanese onsen bath and sound-healing room, Gerber is now nursing a glass of fine Swiss wine, looking out over emerald woodland from the terrace. He is dressed in white trousers and an open-neck shirt. A swimming pool glistens below us. The clang of cowbells can be heard in the background.

Indoors, a 33ft Murano glass chandelier dominates the double-height living room, while a secret bar is hidden behind a bookcase. A chef prepares our three-course dinner, but often Jil cooks for clients whom they often entertain. “Often they haven’t had a home-cooked meal in a home environment since childhood.” Their guest before me was the Duchess of York, there to explore mental health advocacy.

He’s had a long day, which included bolstering staff after one client was “quite mean to them … it’s a cultural thing. The patience and the kindness you need to show is sometimes taxing.”

Tomorrow will start early with a high-profile Turkish family wanting to check out the facilities. Gerber has worked non-stop for years to build his client base, with his first major mental health wobble coming during Covid. “Mental health issues were on the rise, but borders were closed. I should have declared bankruptcy, but I was like, ‘I’m not giving this up.’ It was so close to my heart,” he says.

The business survived but there were further grapples with a “toxic” business partner. “It really took a mental toll.” At the same time, Gerber’s nine-year marriage began falling apart. “I was having a midlife crisis, my six-year-old son was not doing well in kindergarten and as a parent you take on that energy. I was wondering, what is it all for. I was well-off but I’d been much happier as a student watching my budget, not knowing how I’d pay my rent the following month.”

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In 2022, Gerber suffered his first depressive episode. “I just didn’t function. I felt no pleasure. I was deeply sad.” His team would advise he cut down on work and he tried to immerse himself in nature. Symptoms alleviated and he stumbled on for a few more months, but then he and his ex-wife decided definitively to end the marriage, although for several months they still shared a house.

“I had anxiety attacks for days, when I would not be able to leave the bed but my intellect was on, so it felt like I was observing what was happening to me. I remember my now ex-wife said, after a day or so, ‘Look, I’ll open the window, why don’t you take a fresh, crisp breath of air?’ It was two steps from the bed, but I was helpless, crying because it was too much for me to do that.”

He was told he needed clinical help. Treatment at Paracelsus “would not have been therapeutic”, he says, so instead he waited for a place in another clinic. During that time he hosted several Paracelsus-related events.

“I had to put on a good show because there was no one else to step in. I had one speaking engagement at a family wealth business conference in a private château outside Paris. I sat in the beautiful library just before the speech, crying my eyes out. I made it onstage and the feedback was amazing because I came across as so authentic,” he says, but for two days afterwards he couldn’t get out of bed. “I began to see how we can warn CEOs all we like about burnout, but they’ll hold on until the last straw breaks.”

Eventually, he spent six weeks in a nearby clinic with a 70-patient capacity. “It was a very different programme to here, a much lighter touch, much less personal. But it really did me good.”

Ever the businessman, Gerber instantly grasped how the experience could help Paracelsus Recovery to improve. “I came out with real, lived experience of what our clients go through. I’ve always been a compassionate person, but before my understanding was intellectual. I had a good life, I didn’t understand what pain actually feels like, when you can’t function any more.”

He also recognised many aspects of himself in the Succession crowd that his business treats. “Even in the early days when I didn’t have much, I would not have wanted to change places with any of our clients. I’ve always been mindful of that, but at the same time, through my own insecurities and dopamine system I fell into the same patterns as some of them.

“I like nice houses, cars and vacations in five-star hotels — I always thought once I had them, I would be happy ever after. But you realise to a point, the emotional void isn’t medicated by any of that — in fact, the more possessions you have the worse it becomes.”

Like so many of his clients, Gerber was what the former prime minister Theresa May once described as a “citizen of nowhere”, who had studied and worked all over the world but lacked connections. “I see it with so many clients who have homes everywhere, they go to Paris to shop and then they’re like, ‘Actually, the weather’s not that good, we’re bored, let’s go to LA,’ where they have a massive estate. But when did they last enjoy nature, walk in the forest and hear the birds chirp and feel the sun on their skin? It’s a cliché, but it’s what we need to do.”

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He focused on putting down roots, but even in prosperous, egalitarian Switzerland, Gerber was aware that his house was bigger than his neighbours’ and that — however friendly he was — “we were never invited to dog sit or babysit. They would presume we were too busy or too good for that kind of thing — it makes you feel othered.

“And in other countries, it’s a whole different ball game, where wealthy people live completely separate lives with a wall of barbed wire behind them. Of course, you can still live in a small house and drive a Toyota, but it’s hard to go back to that when you’re used to comforts.”

Now, he’s learning to wean himself off luxuries. “At first, these things are wonderful. When it becomes the norm, it doesn’t give you pleasure. I’ve done some amazing travels, but I told Jil a year or so ago, ‘I’m kind of fed up with the Four Seasons [hotel chain], can we go camping?’”

The black dog continues to plague him, the worst episode being last autumn in the Seychelles, with another plummet in April that’s left him struggling with brain fog. “It’s slowly getting better, but I’m still quite a distance from the ‘old’ Jan,” he says.

After we meet, he and Jil marry in their garden (“For the first time in my life I’m with someone with whom I don’t have to play a role, I’m authentic me”) and head off to India for a two-month, off-grid ayurvedic retreat.

Gerber knows that stories about the one per cent’s pain are usually greeted with howls of derision, but his compassion for his clients has only deepened. “People always tell me it’s easier to feel sorry for somebody living on the streets than for somebody in a gated cage. But I can have empathy for both.”