Can be many, if not greedy.. but can be broke all too ,but i never heard people earn money by just gambling.
But gambling gives them fun and excitement,that makes them gamble even they had no chance of winning.
Most gambling games you cant win money but there are some rare cases where people strike a big jackpot. The interesting is that a lot of people dont know how to keep their money and they end up betting even more.
That's what you called greedy, betting All of your jackpot winnings continously for the aim of hitting the jackpot again but luck isn't there a the time that's why some loses a their winnings included their capital. There's no good of being greedy in any thing, either on gambling or on daily life. Gambling could not guarantee how much you could earn a day/week/month it all depends on luck. Period