I generally try not to go into conspiracy theory territory but you’ve made a lot of solid, though speculative, points.
Gambling is an excellent way to launder money. AirBnB is an excellent resource for arranging meetings for transfers.
The biggest question is did he go rogue? If so, why?
An agent is different from an officer. While an officer can, say, go to the boss' softball game, to to HQ, ect, an agent is different:
Ideally an agent remains unwitting to his actual paymasters are. That way if things go bad the agent can be burned with almost total impunity and there are no repercussions.
For this guy to have become extremely angry with a dramatic lashing out in the manner we see at Mandalay Bay, it's not an actual requirement that he KNEW he was, say, trying to get back at the CIA or FBI.
Because it's possible he thought he was working for someone else, a key way in which this would differ from Fast & Furious, in which gun stores and transfer agents had been approached directly.
There are a couple of things to surmout in order to make the "Gun deal gone bad" theory stick:
1.) Oh, so the deal just happened to be scheduled as a 22,000 person concert was going on nearby, huh..?
2.) Why are there these other records of Paddock staying at concert-facing high-rise hotels at 2 other locations at American locations very far away..? He's finnicky about having live music for his gun deals, huh...? Isn't this instead the prey stalking behavior of a VERY angry person whose focus isn't actuall on gun deals..?
So as you can read, I'm still unclear.