Here's what I think after playing dice on various gambling sites for more than 5 years.
On a site with 1% house edge, 50.50% of all the money wagered there are losses, and 49.50% are winnings. Although there are more money lost on such a site than won, surely there are some people who are in profit from playing this game for years. I personally know couple of guys from PD chat whose overall profits were above 3 BTC at the time it was possible to see it, one year ago or so.
My point is that, contrary to popular belief, not all players are losing in the long run playing luck based games, such as dice. Yes, most of them do lose, but not all of them. This game would be abandoned by now, if it were otherwise.
Is there a popular belief saying that all players lose in the long run? You do lose as soon as you don't accept the fact that you've won and turn greedy. It's the brain thinking
"If I earned 10% profit so easily, I can earn 10% more again!" and making you believe constant and consecutive wins are achievable.
This is how most players lose. It's a game of luck & addiction. Your brain will want to see that second win, and then the third and so on.. until you lose and then repeat