The rake is a rake on the pot. So if you are playing .01/.02 and the pot reaches $1.00 a 5% rake is .05., or 2.25BB. The rake isn't even taken on pre-flop pots, it's capped, and here's the kicker, the rake is taken from winners, not losers. Losers are going to lose the same amount whether there is a rake or not. It's the winners who pay. So you only have to worry about the rake if you are a winner, not a loser. It's sort of a like a tax on the wealthy. So if you come in and win few pots the rake isn't the problem that caused you to lose.
Look at it this way. Suppose there was one player who in play money games contributed 5% to every pot you won. Now suppose when you move to real money
games that player is no longer there and you don't get that 5%. Do you really think him not being there is going to be the difference between you being profitable or not?
I'm not saying the rake doesn't hurt. I'm just saying it's not close to the primary
reason there are a lot of losers. It might tip the scale against some close-to-breakeven players, but it's not what creates the majority of the losers.