Take it with a grain of salt, but: https://hbr.org/2018/07/research-the-average-age-of-a-succes...

This matches my personal anecdata as well. Locally there are a number of tech startups founded by people in their 20s, but the ones that have gotten significant traction have been older. Which, at 38, keeps me from being discouraged. I mostly love my current gig, but there's a pretty solid chance that it'll be the last employer/employee relationship for me for a while.