If people didn't ever turn a profit then why would they keep putting money in?
We'll assume you're asking questions to decide whether or not you want to make money off poker.
Here's my advice.
Play first, a lot. Get a feel of the game. Then read. Anything and everything and try to incorporate new ideas. Never stop learning. Knowledge will always give you an edge over your opponents. At first you will lose. Then you might win. Then you'll probably lose it all. Then you'll find the common ground, the poker money trade. Then you'll need to develop past that.