I agree start-ups have become in vogue recently and many young, impressionable 20 somethings (myself included) get caught in the Tech Crunch celebrity of it all

I agree start-ups have become in vogue recently and many young, impressionable 20 somethings (myself included) get caught in the Tech Crunch celebrity of it all, but the person you're describing is exactly the kind of person doing start-ups for the wrong reasons. Start with your passion and build a business around it. If the business end never works out, at least you got to work on something you really enjoy. Much harder said than done. Many people don't know what they're truly passionate about until their 30-40s.