You write. . .
Keep in mind the casino pays gaming tax even if the "WHALE" doesn't pay the marker back.

At just what point does the reporting go to IRS. I have never seen them stop a game and say, "Hey you with all the Black Chips down there let us see your Id and Social Security No so we can report on your winnings.

But just win $1200.00 on a Slot and they are all over you.