As a counterpoint, I really think my formal education was valuable for me, and I'm glad I didn't quit to go work on something for one or two extra years. Also, whether or not it's justified, my impression is that there is some stigma about not having graduated from college among many hiring managers.

Basically, don't drop out of college just because someone on the internet tells you to, think it through.

If you get into YC and it looks possible to raise a big round, then it might be time to start thinking about dropping out more seriously.