Why people struggle at 1/2

[waynethetrain]

I have the bankroll for $2-$4 but haven't moved up because I don't have good enough results at $1-$2 to give me the confidence to do so. I was going to wait until I demonstrated a significant edge over a long period (not just an edge).

Is anyone that has made the leap from .50-$1.00, to $1-$2, to $2-$4 suggesting that $2-$4 may actually be easier to win at because of the better rake schedule?