I don't think the restriction is right because of course anyone who wants to gamble will find a way to do it.
Legally speaking, it's the right thing to do for a casino and you as a user, if you are not wanted in the casino, then why are you using it for starters?
If a casino blocks your funds after discovering that you are from a restricted region, will you blame them?
Especially in recent times when technology has increased so much, it is almost impossible to prevent this. For example, this can be removed by using a VPN. Therefore, blocking sites has no practical use.
VPN detection is also possible in some sites, so don't think just because you are using a VPN, they may not know. They can. There is also another layer which is KYC verification. The day you are asked for KYC verification is when you realize that you are going to be busted. Your location on the KYC documents will completely be different from that of your IP logs. What explanation will you give them?