You can consider it as a scam if it did something that is against the law or that is really inappropriate for instance you just won a big amount of money and they will do anything to delay it or in case won't allow you to withdraw and you submitted the required document but still, they did not accept it even though you know that what you have send is valid and doesn't have any problem.
I think you should away on those kind of gambling site.
Even though the ops stated clearly that he didn't know that the casino will ask for kyc but after he won an amount that is above many casino trence hold for kyc demand, because most of the casino may allow you to withdraw any amount that is below $5k but any winning above that limit will trigger kyc demand and the player will need to go through kyc verifications.
But in a situation where the player passed all the verification process and the casino refused to grant him access to the fund then he can call the scam.
Whatever OP or his close one has gone through doesn't specifically make the casino a scam, even if the casino doesn't show it in the beginning or ask for KYC for deposits or even small withdrawals but if you opt for a bigger withdrawal, you are subject to KYC in almost any gambling platform that has a license and is operating by complying with all the rules and regulations like AML, etc.
Casinos have some things that they need to take care of, and fighting money laundering and avoiding it to happen within their platforms is probably at the top of their priority list, so they are not wrong in asking for KYC, and if someone fails to pass KYC, they might be the one who is wrong and not the platform.