As you said, if the casino is such that restrict our country, we should not play smart but abide by it. After all, such a casino is not the only caisno in the universe.
Unfortunately when gambling is illegal in your country, most of the top casinos would also comply and will not cater your country. maybe there are some out there that will cater, but you have a pause for a while and question their reputation as there are only few license provider in the industry and most of them have a similar rules. That's why some people are using VPN to gamble, but it's cheating, so they have to be aware of the consequences but if they accept the risk and possible consequences, then that's really up to them, what they just like is to enjoy in any available ways.
I am aware of what you replied with but it is a bit different from what I stated above. This is not the case of the country of the gambler disallowing him to gamble but the case of the casino restricting the citizen of a certain country from gambling on their platforms. They are two different things. This means that gambling is not illegal in the country of the person, other casinos are doing just fine there, but some casinos are not just allowing them to gamble due to restriction rules. This is common today for many reasons which could include the regulation and cooperation of the countries in which the casinos are domiciled and the gambler lives in, their relationship may not be cordial in gambling regards. Many other reasons must have caused it as well, which is like the prevention of capital flight through that, and many more.