2. I'd say If you used VPN and Gambling sites disallowed using VPN, you might get banned because violating their TOS.
I think he lives in country where gambling site has been banned and using VPN for bypass it, and not about increase the winning chances.
Some of the gambling sites have some sort of tracking their players location. It should be obvious that if on multiple logins, their player established a different country login regularly then it's noticeable.
If using VPN or any other related thing to that is prohibited in some of the gamblin sites then no way it can be used by those people who came from the country that gambling is banned. Better accept the fact that they can't do gambled in an easy way.
They might think that your account is owned by other people that have used by that IP, that fall under multiple account and yeah , a ground for ban or suspension.
Thought regardless if you use vpn or proxy, or change isp, the result of the game will never be affected because gambling games are dependent on internal system.