This advice is for 14/15 year olds. I think the advice would be different for 22-year-olds. It would be different still for 35-year-olds.
22-year-olds have a hard time selling to enterprises, 14-year-olds will find it impossible. Whereas if they build something cool that they and their friends love they will gain many of the skills that might be useful later on.
PG has made the point many times that the superpower 22-year-olds have is that they can live on ramen and work 16 hours a day. The superpower that 14-year-olds have is that (in many cases) they don't even need to find the $1,000 a month to survive.