Borrowing a document from other people to fulfil the KYC requirement is not a good option but some people still use that to get the bonus from casino. They don't think much about the risk that they can get when casino know what they do. Maybe that will not happen in short run but that will cause a problem in the long run. But those people will not care because as long as they can get the benefit from casino, they will still do that and even they may reopen more accounts and use the other people's document to chase what they want. That is why the cheat gamblers will always found the way to stay at the casino and get the benefits of that before the casino found them.
Cheaters always somehow think that they are never going to get caught and then they will always be the one to act upset when they get caught when they should have known from the very start what could be the consequences of their actions. They should have thought that whatever the consequence was, it was worth the risk because of the benefits they will receive. But they do not seem to be prepared when they get caught. I do not understand how they could do this without feeling scared at all LOL. That takes some bravery.