It's not a matter of reward or punishment. It's a matter of the skills required for continued success.

Early startups require big risk-taking, progressing at an absurd speed, charisma to get investor capital, and really just being a little crazy.

Once the concept is proven to be viable and potentially profitable, the focus needs to shift from proving it can work to making it sustainable. This involves less risk, process improvements to avoid issues like getting sued, better money management, more careful time management to avoid burnout of non-founder employees, and generally just being more rational about things.

It's rare that a person can exhibit both of these sets of behaviors, so companies will often swap out the former for the latter as a company matures. If they didn't, the founders might unintentionally drive the company into the ground by taking unnecessary risks after finding something that already works.

Does that answer your question, or did I miss the mark, still?