I believe paddock was duped into thinking he was making an arms sale but he was really a decoy who was killed before hand to a terrorist event planned away ahead of time
The article recently about an ISIS attack foiled in NYC mentioned an informant who had suggested to them killing a lot of people at a music event, and the ISIS guys figured out he was an informant. Probably was Paddock. Operation was, imho, a sting that went very bad.