Gambling is just so addicting and this is all because of the fact that its very enjoying for a long time period plus a lot of people get greedy too.
Yes people get too greedy and stay doing it over and over till the lost everything, they want to win their money back and are coming back again and again.
People tend to become addicted to gambling because in their minds, when they lose, there is hope that in another day they'll get lucky and be able to restore all of their defeat. And when won, they assume that they can earn money the easy way, and they will tend to do so, again and again. The circle will take place continually.