A KYC at an online casino is not a big problem in itself. Many players have gotten used to that. It only becomes a problem if players refuse to provide this information. Often referred to as the terms and conditions, they almost always state that the casino reserves the right to perform the KYC, which will happen. Then it is only a matter of time before that takes place. A KYC can, however, be carried out in 24 hours. I often wonder how casinos check such information, since they don't have access to the local authorities for information
As far as I know there are services which are completely dedicated to gather as much information about people around the world as possible and if a casino hires them then they do not need to conduct any kind of verification by themselves, they just turn the documents to that company and the company makes the research in their place and tells them if everything is in order, or at least that is the way it works with fiat gambling so I am not sure if cryptocurrency casinos operate in the same way.