Because gambling let you win in the first time because they know you will greed so people are thinking that it is easy to win big in gambling.
But they do not know it is gambling.. Also many gambling site are always offering some promotion. that can attractive to stay long in gambling..
I am not sure gambling let win in the first time
If like thay it's big a chance to get a lot of money
If you already win in the first time its time to stop.