Yeah, This is dangerous for those user that selling there verified gambling account in the market. I saw many users before that selling this kind of accounts and most probably it was hacked account. Worst scenario was your KYC account got hacked and used to cheat in the casino while you have the ID for the casino to trace and sue you for the violations that scammer did. This is what I’m avoiding too on submitting my KYC on casino.
Due to hacked accounts and fraudulent users, the casinos themselves suffer. After all, if a player has conceived fraud, then even despite the presence of KYC, he will use a fraudulent or hacked account.
On any forms of business, there will always be abusers like that but business owners can do something to stop them. If it's an online casino then they can increase their website's security and they can also enforce a KYC to intimidate those who will try to abuse their sites but if ever the abusers insist to and they are caught out, it will be easier for the casino to trace them.
Some criminals will just hack someone's account that are verified already by a KYC and they will use it for their exploits. Problems like this will be solved out easily if a user who got hacked will cooperate on the casinos immediately and then the casino will freeze their accounts.