I'm sure anyone who has had bad luck in betting, they will have a negative effect on themselves, regardless of addiction.
The losses in gambling or bad luck will only have a negative effect when a player uses money that is not free.
I think what the OP mentioned is more towards crime and character, my understanding is that addiction doesn't harm other people, tend to be more addicted to themselves in making gambling bets, maybe they will sell theirs to bet.
Addiction is an uncontrollable urge so an addicted person will do everything to get money for gambling. That includes embezzling funds, and committing crimes like thief and robbery in order to get money for gambling. Thus, the addiction does harm other people.