Because you can 'possibly' earn quick and easy money and not have to wrok. Bums like not working so tell themselves they will continue to try and chase their winnings. They all lose and cry in the end.
Indeed the fact is that you can addicted too it and that it is addicted due to the fact its enjoying and that you can earn some nice money.
That two things one is the fun in these games of gambling and the other is the wish of earning bigger in gambling makes a person addicted to gambling and if he find some other place for these two things or at least for earning money then he do not become addicted but give only some time to gambling.