The truth is that gambling is not wrong, it's just that when a gambler has reached a situation of gambling addiction, it often leads to spending more money outside the gambling budget, of course this has an impact on real life. Gambling responsibly is always a gambler's best option for better financial control, but it's not uncommon for that rule to be broken because the gambler has been caught up in the illusion of winning.
It becomes wrong when it affects the gambler badly and when they start to act abnormally and does crazy stuff. Selling of their important things just for them to gamble. That's severe addiction in there and although it's still need some clinical diagnosis for one to tell if it's severe or not. The actions that they are showing to the others signifies that they're an actual addicted gambler. It becomes bad in many forms where each gambler should be responsible for all of the actions that we do. Simple broken rules that we set for ourselves means that we're not committed or we're already out of the control of ourselves.