Some people clock out at five. Andrew Feldman keeps going until the lights go out — and even then, the lights in his head probably stay on. For AI chipmaker Cerebras Systems CEO and co-founder Andrew Feldman, the idea that greatness can be built on a 38-hour workweek isn’t just wrong.

In October, Feldman appeared on the “20VC” podcast with host Harry Stebbings and offered a no-frills reality check to anyone hoping to build an empire without sacrificing sleep, weekends, or balance. And in the same breath, he dropped one of the most brutally honest assessments of the startup grind.

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After complimenting Stebbings’ writing on the harsh realities of entrepreneurship, Feldman said the posts “have the feel of what my life is,” then laid it out plainly:

“This notion that somehow you can achieve greatness. You can build something extraordinary by working 38 hours a week and having work-life balance. That is mind-boggling to me. It’s not true in any part of life.”

He didn’t stop there.

“You can have a great life. You can do many really good things and there are lots of paths to happiness,” he said on the podcast. “But the path to build something new out of nothing and make it great isn’t part-time work. It isn’t 30, 40, 50 hours a week. It’s every waking minute.”

Feldman compared the startup lifestyle to elite athletes like soccer player Cristiano Ronaldo — the kind who track every meal, every stretch, every minute of recovery like it’s game-day strategy.

“Rest isn’t rest,” he said. “Rest is something you work on so your body rejuvenates faster.”

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At the time of the podcast, Cerebras Systems had recently secured an $8.1 billion valuation after closing a $1.1 billion Series G funding round.

But that was just the warmup.

Earlier this month, Cerebras locked in another $1 billion during a Series H raise — this time pushing its valuation to roughly $23 billion. The round was led by Tiger Global and included heavy-hitters like Fidelity, Advanced Micro Devices, Benchmark, and Coatue.