Risk does not necessarily mean financial risk. There's a lot more being risked doing a startup than cash, and those things should be pretty obvious, though maybe not everyone sees them as risks. I can think of a few and I've never done a startup. Reputation, mental health, credibility, friends and business associates, future job prospects, legal risks, etc. Fuck up a startup bad enough and even if you have millions in the bank you could have lost all of the things I just listed.