I don’t know the details of Trump’s casino write off but I would guess that it was a capital investment in a business enterprise that went bad, so he (through whatever vehicle(s) he used to make the investment) could write it off against capital gains. Could be several entities or pass through entities that made the investment, and thus could write it off.
Trump also bankrupted a few businesses. All legal. It happens. That’s capitalism.
Many of the Trump properties were not his. They paid to use his name.
I wasn’t criticizing Trump for his bankruptcies. He’s had only 7 vs 519 (or something) functional businesses. I was only stating that Trump stretched his losses over the last 40 years and it totalled at least a billion dollars.
I have no criticism about anybody who takes chances, even when it doesn’t work out for them.