First time I went to Vegas, girlfriend and I woke up early (7am or so) and went to play some $1 blackjack. We sat a table and this guy was completely wasted, betting $20-$50/hand, and losing every time. Once he lost his money, he'd get up, go to an ATM, come back a few minutes later, and repeat the process. He probably went through a good $1k in the time we were there. The dealer said that the guy had been playing since like midnight or something. Ridiculous.
That said, I did come out ahead by 40% when I went to Vegas for a conference last year. I put $5 in the slot machine and got $7 back! I beat the house!