For me the main issue is that as you get older the barrier to entry for you to move from Job -> Startup gets greater.

I'm 29, have 2 mortgages & an amazing son (that my wife looks after - therefore she isn't working anymore). So my responsibilities as a husband & father are to ensure I can continue to provide for my family.

This hasn't stopped my entrepreneurial side at all, but it means that in order for my company to support myself & my cofounder we have to pay ourselves a significant salary compared to renting/working in a house together & not worrying too much about bills/salary.