You can make a living gambling. It's called being a professional gambler. You can't make a living drinking, and most people can't make a living having sex (although some can, but those that do generally stop having fun while they're doing it), but you can definitely make a living as a professional gambler. And when I say making a living, I mean significant amounts of money. There aren't a lot of people doing it, because it's not something that's taught in most schools, and it doesn't come with a very good benefits package, but there are a few people making over $100k a year gambling. (According to gambling author Mason Malmuth, there are probably fewer than 200 people in the USA making this much money gambling.)
It seems incredible that someone could make a living gambling. I mean, let's face it, the casinos wouldn't exist if they could be beaten. And in fact, most casino games and most gambling games CANNOT be beaten. Not in the long run, which is what a professional gambler has to look at if he's going to be good at it. One of the goals I have with this site is to explain the differences between professional gamblers and other gamblers, and help you determine how much professionalism you want to add to your own gambling career.
One of the reasons that people can make a living gambling is that poker has become more popular now than ever, and poker rooms, both legal and underground, both landbased and online, are becoming increasingly accessible. Poker is the #1 game for professional gamblers who want to make a good living. If you can play poker well, you can earn a good living, especially if you play online and are able to play multiple tables.
People cannot become professional gamblers playing other games like craps, roulette, baccarat, keno, or most of the newer casino games like Let it Ride. With the rare exceptions of when the casino is running some kind of promotion where the payouts on the bets are in the players' favor, it is impossible to make a consistent living playing a game with a negative expectation. It's also important to note that most the gambling games and bets we talked about in the previous paragraph have a negative expectation for the player most of the time anyway; it's only in the case of professionals who are willing to master their craft that the player gains the edge on those bets too. (Let's face it--even if you're extremely smart about betting on sports, you still have to overcome the 10% vig from the bookmaker.)
I think that the best reason to gamble is still to have fun. But I'm also firmly of the belief that you'll have more fun when you're winning. You won't learn to become a professional gambler on this site, but you will definitely learn how to win more often and lose less often.