It is not fair if it is not being mentioned on the T&S or ToS, but if it is being mentioned then players should be aware about this thing so players are ready for it once they get a big win. It wont be fair if the casino does not process the withdrawal once player pass the KYC. I wont say that it is a tactic for not paying unless it happens regularly on the site.
Very well said. That is why they informed that they have KYC and they will ask the gambler for documents that will bring in big money in their casino just like the big winner. It is the responsibility of a gambler to know the contents of the ToS first and understand it so that there is no problem in entering and exiting money. If you are not in favor of their rule, you are free not to play here.