I don't think it's complicated though, government could have done their study on whether legalizing gambling is going to be good or bad. And in this case, I'm inclined that they did see more pros of it that's why they approved. And perhaps they have steps or plan already in place if ever there the number of gambling addicts are going to increased. They will have to build rehab facilities for that.
Whether it is because of its advantages or because they are forced to make this decision, because the people have already adopted gambling in their lives, it is based on the losses that the government gets because the people are actively gambling, so the last step that can be taken is that they have to accept gambling as a means for them to benefit from gambling itself, so as not to lose too much.
It's already has a stigma, but perhaps the money that they can generate thru gambling is very big that Thailand is really willing to go 100%. And the government should be in top of everything here, in my opinion and again they have contingency for such disaster and maybe all corners have been covered by them and that they are ready to embraced all the stigma and negativity that will come their way.
The thing that makes us blind is that we don't know how much profit the community gets if it's talking financially, and the simple logic is that casinos can't possibly give alms to every gambler, but if everyone already knows the risks, it is their own choice why they gamble.