Which 4/5? Zuck yes, Bezos no, Page/Brin: doubtful they were early 20s. Maybe 20s, but not early 20s.

EDIT: Page was 25 and Brin was 24: https://en.wikipedia.org/wiki/Larry_Page

There would be another important lesson: don't give up! (it's a true cliché, yes)

I'm 37. I constantly remind myself that Craigslist, Wikipedia, Salesforces, Intel, etc. were founded by someone >=35 years of age[0], and that, since I live a healthy lifestyle have at least 30 great years ahead of me (on average).

https://readwrite.com/2013/09/27/jimmy-wales-to-silicon-vall...

jan koum was ~31, brian acton was ~35 when they started Whatsapp

If you want to waste it working.

If you consider starting your own company a waste, you definitely shouldn't start one.

I always struggled in school, waking up, even as an adult, HAVING to wake up at a particular time, five times a week just made me feel terrible.