I think the main reason why people needs and prefer to gamble because they want an easy to get earnings, less efforts and time. In gambling people tend to satisfy their earnings from gambling even they take risk out of it.
It is true that you could earn easy money on gambling, but don't expect that you could win always whenever you want, it doesn't work like that. Gambling is a very unpredictable game, that is why it is all about luck for me, and I'm not seeing myself playing gambling again, it is not just worth it, I'd rather spend my bitcoin on Trading than on gambling.