It depends on your money you invest, also depends on your luck, your experience with gaming.
So if you are good in playing any game and can have the ability to win, you will earn more there, there is also chances of loss
I don't see gambling as an investment, i prefer to use it for fun. Its normaly to loose when you are gambling, the difficult is winning. If you see it like an invest i will see it as a bad investment. Gambling is only a good investment for gambling companies, they won with the house edge.