Terrible assumption at best, a lie at worst. Putting everything on the line is not the only way to do a start-up that's successful.
People please, while you are at the university ,please, visit some (m)ba lesssons. If you don't have this chance, take advices from someone who you trust and runs a business.
Though, having been to 500Startups and seeing the amount of 20-somethings there, I can't imagine they had much to lose in the first place.
I don't see why this lie of having to put everything on the line is consistently perpetuated within the start-up ecosystem. Yes, start-ups are hard -- but I am getting tired of what seems like a consistently perpetuated lie so that start-ups can feed their own ego -- or worse, justify their failure.
Before the Silly Valley become synonym for a startup/business, whoever wanted to be entrepreneur needed to invest a lot of his/her money to start a business. For example, think about running a "simple" limo service - that requires a lot of investment.
In other words, you cannot assume that you will run startup and if it fails you will have great living like nothing happen. At least in software business you can easily find a job and start saving again.
Also startup is "marathon" and not "sprint" but word "marathon" does not mean you run slow - it only means it takes forever :)