Actually, from what I've heard, most credit cards won't even be accepted at that point since these sites aren't based in the US, if the deposit is too big (which could mean even like $50 or $100) the card will often just deny it.

Either way, I try to withdrawal a few hundred every month because I don't trust holding money on these sites. Who knows when they'll shut down outa the blue or something? Better safe than sorry with all these types of things. You can also try winning $1000 instead.