if KYC is needed, it should be requested as soon as people register. Asking for KYC only when people have funds stuck is a douchebag move, and any company that does this will lose me as a client.
I am sure that 90% of existing online casinos will do exactly this (except for the conditionally top 10). We believe that every client is important for a casino, but in fact they have a huge turnover of newboo players and they all generate income. 1 regular player can be equal to 10 new players, for example, in terms of the benefit received by the casino, but already 15 new players are more interesting than a regular player. Besides, what can you do to a casino? Most often, the “hanging” win will be less than the cost of the legal costs of trying to get this win.