We must not forget that gambling is a source of entertainment. And entertainment is a basic human need. So it may be that the people you see, even those in wheelchairs, are gambling, perhaps they are getting that entertainment or excitement from it that keeps their minds sharp as they get older as from their boringness.
Anyway, if they can afford to gamble at that age, I mean both financially and mentally, then I don't think there's anything wrong with that, they're just getting entertainment from it, and there's no need for us to interfere with these matter.
Maybe older people need rest and entertainment in this way, but I would not like to see these people lose every last cent. I also do not exclude the possibility that some of them are trying to extinguish their depression from loneliness in a way that drives them even deeper into it. However, it is already difficult for older people to dictate anything, because they are older and can say that they have lived their whole lives not to be disturbed or told what to do and how to have fun, as well as what to spend their money on.