At this point, conspiracy theories abound. There may be a grain of truth in several or even many of them, but like blind men trying to describe an elephant by the sense of touch alone, there will be widely varying explanation, which if taken as a whole, do largely explain the enigma.
The key person at the center of this is now dead, apparently by his own hand, with thousands of loose ends which seemingly go nowhere, but then, people are trying to apply logic where none exists.
That is the difference between real life and fiction. Fiction has to make at least some kind of internal sense in connecting one point with the next, while real life has no obligation to make any sense whatsoever.
Did Paddock do the shooting at the Bellagio and the Tropicanna?