Sting gone bad / black swan, these are likely scenarios. Early speculation is he was involved in Fast and Furious. One of his planes was taken off the register, a federal black ops action.
Frankly, the insane thing isn’t cutting it with me. He isnt the type to seek validation as an evil mass murderer. Those are always unsuccessful losers. And yet he attempted at various venues to pull this off. So he was very very motivated if not paid or pushed.
There is more info out there somewhere. This was no snap.
I think all this "extensive preparation", and his "feelers", to the extent of renting rooms, for Lalapalooza in Chicago, and others, IIRC, certify this.
Still, his ultimate motive remains an enigma, to me at least. Unless it is simply misanthropy.
He was a gambler and almost surely a loser. He got royal treatment from the casinos with all the freebies that are given to high roller losers to keep them coming in and leaving money. If the casinos were losing money to him he would not have the perks. In fact, if he were a consistent winner he would be barred from the casinos. So where did his money come from? I would suggest gun dealing. That is where his interest seemed to lie and the gambling would launder many millions even as he “lost” millions at the poker machines. I suspect ties to both CAIR/ISIS and to Antifa, both of them. They are surely allied until they win, then, of course the alliance ends.