Individuals who are constantly searching for someone or something to blame for their losses are not mature. Blaming won't even make up the money you lost; accepting responsibility for your actions is the best course of action. Additionally, I dislike those who criticize or even assign blame, even when their acts were the cause. And the reason they place the blame is that they always strive to appear flawless, as though they never make mistakes, and when professionals falter, it speaks more well of common people.
When the time comes when they will be unable to place the blame anywhere, they will turn their attention to finding ways to make up for their losses. They fail to see that there is no shame in losing. No one would hold me responsible for introducing them to gambling because I don't even introduce people to it, and even if I did, why would you hold me responsible when it was all a question of choice? Not a single cause to assign blame. Either they blame the casino or say anything it won't change anything.
Some individuals naturally are good at holding an external factor for any misfortune in there life. When they have fortune they take the glory and boast that the fortune is as a result of self effort. Personally, I don't see such people as immature as you noted because some people see it as a big deal accepting failure and so instead of accepting failure they prefer to apportion the blame to a factor so that people will not see them as been misfortune. To them, their concern is not about making better choices next time but to control how people will view their actions.
Unfortunately, such way of living doesn't change anything. If you are unlucky and then blame it on gambling, the fact that you are unlucky haven't changed. My humble advise is that instead of blaming gambling efforts should be made to make corrections subsequently because you function for yourself and so you need to make life worth living for yourself and so should blame gambling at all when things doesn't go as desired.