Money was invented as a medium for exchanging value:
you give me value, I give you money,
then you give someone money, and they give you value.
In this scheme, the person who ends up with more money is the one who has provided more value to others. Everything is clear and fair.
When we win money, we break this scheme. In the same way it is broken by theft, robbery, or taxes. If money is obtained for nothing, it loses its value.
It would be much better to play for something else. For example, for points.
Cryptocurrency actually fits this quite well too. Especially coins that are given away in airdrops, or those that are easy to mine. Or, really, any coin that only pretends to have value.
So overall, it seems quite logical to me that the most popular board on Bitcointalk right now is the "gambling" section. The most obvious use case for cryptocurrency, wouldn't you agree?
Casino to the best of my understanding are actually providing value in place of our money, whether you agree with this or not, Fun is a value that is worth paying for and this is what casinos are providing, same way other games with in-app purchases provide fun as value and I return, we spend our money on their things they sale as in-game items.
We go to the movies, pay for a movie ticket all because we want to watch our favorite movies, it's fun right, and that is the value we pay for.
So for me, I feel that winning money from casinos is not the same as stealing, carrying out a theft, robbery or any sort of this, but simply a means through which the casinos give something back to their users they provide fun as value to.
I hope this make sense..