VPN is not recommended to bypass the country restriction by the casino but it is fine/safe enough to bypass the restriction by providers. I was actively playing in duelbits since the first day and I always use VPN when I want to play slot from some specific providers because I cant play it without VPN. At least I have never experienced any effect of using VPN so far although I have never made a huge win (max few thousands $ only).
When I tried to play games on some providers it says that it was not available in my country, I think this is still a country restriction so bypassing this can be illegal? there are still lots of games anyway lying around that I can play with no issues so I guess I will just stick on them. You never made a huge win but you made a max thousand dollars? But, this one you made sounds bigger than a huge win. Good for you that you have safely withdrawn all your wins without being questioned that you are using a VPN but duelbits is a legit casino anyway, that can be the reason and if you play on a not known casino, you won't also do these things right?