gambling becomes addictive when user gets unexpected winning, that too large sum easily Keep the people under the wings to spend more even on experiencing continued fail after a big win.
To get addicted with gambling, the gambler does not need to win big but just hearing such a big winning of other gambler's itself makes them motivated to keep on playing. This type of gamblers are always getting greedy over time because they always want to win big again and again or want to copy how other gamblers are going.
Not only gambling everywhere addiction happens.
Yes, every where it happens because being greedy is a common characteristics of all human and we are not getting into the practice of controlling it, that must be the prime reason for it.