Don't forget why YC wants more young people to work for startups, they benefit from couple of successes and their metric is to increase number of companies they want to invest, which requires more number of cheap engineers/interns giving their life.
Your chances of success is lower than YC's chances of success because they invest to many companies in parallel, but you can only work for 1 company
Understanding people and companies incentives doesn't mean that it is inherently bad as you are implying. YC is also investing in a bunch of people and putting money towards new ideas. Lets not forget that innovation is difficult and fraught with failure.
People who want to go that route and feel strongly about it should give it a shot with their eyes open.