If you are good? I doubt you would make a lot of XP on long term...
I shouldn't disclose that kind of information, but if I used my trade profits to buy xp, it would represent more than what I get through actually playing the game. I don't play
that much but still. 10 minutes of browsergaming would easily beat 1 hour of playing cRPG.
Also, my profits are quite stable. I don't trade items, because this tends to be veeeery slow and I don't know the item values that good. I only do LP buy and sell and occasionally being a 3rd party in a trade to circumvent the tax, and that isn't going to fail anytime soon.