His advice is:

- Work on a personal project that is motivating to you (obviously you won't work on it if it's not motivating to you)

- It's a good sign if the project you're motivated to work on solves a problem that you and your friends care a lot about, because there's a good chance many more people will also want that problem solved and will buy/use your product.

Sure, plenty of big companies were started via different paths, but not many were founded by kids barely out of high school.