What Dev said.
Also, as the stakes increase you will run into more "solid" players, the wreckless ones play a little better, but the really big deal is the lower rake.
In California most cards rooms are $1 pre-flop, $5 on the flop plus toke.
HUGE difference between $2/$3 ($300 max), $3/$5 ($300 max), $5/$5 ($1000 max), $5/$10 ($1000 max) in terms of what % of the pot goes into the box.