And on the casino side being an admin, you shouldn't be nervous if you have found a player like that on your website.
As long as the "dangerous player" isn't a hacker or does not exploit the casino's vulnerability lol.
^This could be some of the things the casinos are worried about. This is probably why they put in some checks to investigate some extraordinary wins before the winners are allowed to withdraw their wins
the whole story i think that is pretty normal , until there is a repeating action over and over again like making big one bet, won it and leave then repeat. that could be something , the meaning of -dangerous- player itself could be interpreted as someone who trying to exploit their casino and it is worth to check.
if he did not make any losses during that period repeatedly , that what makes any casino owner worry.
also pointing about the instant cashout , it has been a risk taking for the casino owner, they do know the consequences about that right?