Bitcoin is a get not wealthy slowly project. Yes some people did spectacularly well, but even if you were looking at a three month payback on $10k of kit like it was back in June, that's only $100/day. With difficulty and price changes (like D&T said), the payback is longer, and realistically, a $10k mine places other stress on your accommodation if you're doing it at home (excess heat is a big one - I'd hate to think what 10 to 40 GPUs would be like in a dorm room!? I at least hove my small grounp of computers at the other end of my house).
If you want to get into computers and maybe bitcoin, then experiment and work it out with one or two rigs. do it because you can afford to, not because you need the profits.