I have heard and even witnessed something like this happened. At the end of the day, it is the bettor who is at fault for falling into the trap set, but of course the gambling company has a lot of role to play in triggering the gamblers. Gamblers has the power to reject or let themselves be under the influence of their addiction once again. I just hire that they seek whatever help they need, especially professional help.
Yes, gamblers should take full responsibility just like shopaholics, alcoholics and other people with addictions. If we start dividing this responsibility between those who advertise (of their product which, when used in reasonable quantities, does no harm) with people who consume it uncontrollably and face unpleasant consequences, we will harm all parties.
Still, gamblers have to be held accountable because it is their risk of becoming addicted. But sadly, not many can realize this and are drawn even deeper into gambling. I think this is a shared responsibility between gamblers, advertisers and casinos but I don't know, it seems that casinos and advertisers keep going without thinking about the fate of gamblers who are addicted to gambling.