You forgot something important the risk of buying gambling accounts. I know that all advantages you can get with high roller accounts (higher faucet, rakeback, or other bonuses). But when admin know if the account has changed hands (he noticed it from different IP, or other else) he can ban your account and you will get nothing in the end from purcashing the account
When you want to log in from different IP usually you need to confirm new IP through the mail and that's all... I play from different places, one IP from home, one at work, when I travel I have my laptop with me so new IP... I doubt that your account will get banned just because you changed IP! As I said, with new IP or a new device you will have to confirm that is really you and you can play!
So the only important risk is that when buying an account your mail address has to be changed on the site, or to buy an account with the mail! If not, you risk to buy it and the owner can take it back!