We at Business Start-Ups often wonder what it's like to be millionaires. You could say we're a bit obsessed with the idea. And young millionaires? Oh, please. We can't get enough of them. Can you blame us? It'd be pretty awesome to wake up in the morning and know your business will have a good day--a very good day. But what does your millionaire dream look like? If it's anything like the ones of these entrepreneurs, all of whom have hit the million-dollar mark before hitting 30, you may just see your dreams reach fruition.