What's there to understand? Trump has very little of his own money at risk. He uses "investor's money". Trump's casinos have outstanding debt on their very high interest rate bank loans. When they declare bankruptcy as Trump as done several times now... the lenders don't want Trump's property as they have no idea how to run it ... so they reduce Trump's debt load in order to keep him in business by lowering the interest rate to Trump.

Sounds like a pretty smart operator to me.