So why are we not being told about possible motive? What is going on here?
Maybe he wanted to lower value of the casino stocks.
The guy is dead, he's not talking. He didn't leave a note and has no obvious motive. It's not a matter of not being told, it's a matter of not knowing. Not knowing doesn't mean there wasn't one. Obviously there was one, even if it was nutty. But maybe that's what it was, nutty.