Think of it as they spent that money to buy a painting or classic car, would you call them losers?
I will not call them as a loser, because they know how to spend the money on their hobby. People who still have money while they are playing gambling and decide to end the game and quit to gamble will be the winner because they can control their passion for gambling. Maybe they can call as the winner in gambling.
Winning is what you make of it basically. For some people it's about the prize money, in which case few can be called winners lol. There are also those that, as you've said, is playing for satisfaction and just for the experience. I think this category has more winners than the other one.