He was on trial for taking loans on fake gains.

That’s not quite right.

If you buy something for 300m, with 200m in loans, and sell it for 250m, you pay the loan back first, and have 50m in losses. Your taxes go down.

He only pays tax on gains.

Remember the whole case is him inflating property value to get loans. Between the fire sale, and the bad loans, it’s very likely he has little to no equity. He could sell all he has and not have any money to pay the $500m (plus interest.) Which also means little to no tax burden.