I agree Luvepoker and believe the % of players that are winning players is between 8-15%.
When I say winning I mean those who actually withdraw and spend the money on other things outside of poker and don't have to redeposit or go bust.
Why do I believe it's so little? Well most the human race aren't good a number of things that are needed and required to be a winning player(long term) besides being good at poker. Any dummy can read a book, lean a TAG style of poker and use charts. What most the human race aren't good at is the following:
1)
bankroll management. If you can't make and keep within a monthly budget(in real life) you can't manage a poker bankroll. That alone makes you losing player long term doesn't matter how good you are at poker. This alone likely covers and turns 75+% of the human race into losing players.
2) Patience. Should be obvious why it's needed.
3) Mental toughness/tilt control. Again should be obvious why it's needed.
Cheers!!!