why do i win more at 15/30 and 30/60 than 5/10?

[housenuts]

I don't understand this. Why do I win more at the higher levels? I think it is because there aren't as many stupid fish!!!! I mean at 5/10 and 3/6 people always suck out on me. I'll cap it preflop, and then check-raise someone on the flop with AA and they will hit a runner-runner straight to beat me! I think I should just play at the higher levels because this doesn't happen and you can actually bluff people and they will fold when they have runner-runner draws instead of always sucking out!
What do you think? Should I move up permanently?