What strategy do gambling developers to expand their market to countries which do not allow any type of gambling?
Do they continue with allowing users to use VPN, or do they have "some trick"?
Allowing users to use VPN is one of the possible ways to deal with the ban by the government, the other possible way is by providing mirror links like what Stake does.
If you are familiar with Indonesian local gambling sites, you should have known that most Indonesian local gambling sites provide a special link(s) to their players so they can bypass the ban/block.
I think these 2 ways are the most common thing which is used by online casinos that operate in a country where gambling is something prohibited.
Using VPN is the most common way to pursue gambling despite the restrictions and gambling blocking in a country. However, some reputable casino sites don't allow it. As for me, it will be better to follow the government rather than break the law. It will be better to avoid illegalities, especially if pursuing gambling has consequences in a country. There are still other ways for us to gamble but we should avoid what the government disallows.