The idea that this is means "you don’t learn the actually valuable lessons" is completely baffling to me.
Most people I've know with founding engineer experience or similar leave not because it's not challenging, but because it's exhausting.
Increasingly I've realized that the HN community and I are not even speaking the same language.
Even in areas where startups aren't literally creating new product categories like the foundational model providers, the edge of a startup over a more established business is the speed at which they can provide value. What's the point of buying CoolCo when you can go with L&M Inc. that has thousands of headcount working on your feature. The value prop of CoolCo is that CoolCo can roll out a feature in the time it takes L&M to make a detailed specification and a quarterly planning doc breaking down the roadmap and the order of feature implementation.