At their age I went to graduate school in math. Which was a longer time commitment, at lower likely salaries, which left me with no real employable skills.
I do not see a failed startup at that age as a worse economic choice than graduate school was for me.
Losing 1-3 years of career development by working at a failed startup with other 20-somethings from whom you have nothing to learn is a very expensive career choice -- unless we do actually live in a bubble of vapid startups in which actually being good at your job (whether it's programming, business development, or otherwise) doesn't actually matter.
That's not even factoring in the broader opportunity costs, actual cash outlay, etc.
At their age I went to graduate school in math. Which was a longer time commitment, at lower likely salaries, which left me with no real employable skills.
I do not see a failed startup at that age as a worse economic choice than graduate school was for me.