@Smokin Joe
Remember though that Paddock is alleged to have been off his rocker. Irrational people don't think rationally. He may have become angry, blamed the casinos, blamed the musicians and the audience at the concert, blamed everyone but himself for his reversal of fortune. Who knows what might have been going through his mind when he planned and executed this mass murder?
He was found dead in the room. We do not know for certain that he either planned nor that he, alone, executed the mass murder. Without more evidence, I cannot attribute planning solely to him, nor can I attribute the execution of those plans solely to him. Was he involved? Almost certainly. We can't prove he acted alone, however, and two of those who have contradicted that scenario are already dead, unable to be questioned further.
Although no mention has been made of drugs, we have no toxicological data. We have only a superficial examination of his brain, saying that appeared normal, but no solid cytological data from the M.E. indicating the absence of abnormality.
Maybe he wasn't acting rationally, and maybe he was, just within a demented context. Keep in mind he allegedly assembled more firearms than would be required for the task by any one shooter, easily three times that number, and apparently (though we have no inventory) sufficient ammunition to exact mayhem and murder. He did so without alerting the hotel staff. Crazy like a fox, but not irrational, just rational in a context and with an objective we consider completely inappropriate.
He may have been angry, but we don't know what motivated that anger. He had examined other gatherings, according to some sources, but taken no action, whether out of poor opportunity, or perhaps music more to his taste. I would expect there was more to this than just a losing streak at the machines or the desire to be the ultimate music critic.
You are right in that the machines are set to pay out (over time) generally a percentage from 40 to 75 (or sometimes more) of the money put in. The house doesn't put them there just for decoration; they are money makers. Out of a casino floor of machines, there may be a few which pay out better than the rest, even consistently, but the average visiting player will likely not identify those, and many who 'hit big' will move on because they think the machine will not hit again for a long time after a jackpot.
That isn't how it works. You were either lucky or you found a 'hot' machine. But most people don't understand the calculus of having a few big winners to keep the dream alive for the multitude who are consistently losing 30 to 40 or more cents on every dollar they put in. A lot of that payout percentage is small change, which is cycled through the machine until it is gone or the player relents.
A professional gambler would understand all that. He would recognize that some machines are lemons, others are jewels, and would not likely persist in a losing streak. A compulsive gambler (not necessarily professional) would keep stuffing money in in the certainty that sooner or later they'd get it back (a plot element in a host of sitcom episodes), but a pro knows when to fold 'em and move on. Whether playing nickels or the house limit, though, the house, statistically, will keep a percentage of every wager placed.
If he gambled professionally, (i.e. made a living at it), that's one thing. If it was compulsive, that's another. Either way, he had the means to do so.
Paddock called himself a professional gambler. I think he was a gambling addict. He was reputed to have spent hours at video poker machines. Those machines, like the slots, are rigged in favor of the house. I don't believe a professional gambler would spend so much time at machines. If he was addicted, maybe he just couldn't stop himself and this inability to stop gambling morphed into something more deadly.
I don't know many pros who would rely on machines to make a living. There are a few folks out there who have recognized high payout machines in casinos and done well, but for the most part, they are better to study the odds on a game in which they actually have some control over the outcome other than placing a bet and pushing a button. High limit poker, baccarat, even blackjack allow for some skill factor. Small fortunes, even oil wells, have been won and lost at those. He did have a reputation as a 'whale', a high limit regular, but I doubt he was a consistent high level loser, even though I have no evidence to support that, and it is open to being refuted.
Still, without more data, I am seeing what appears to be dribbles of alleged information which could be intended to provide the basis for assuming he was a raving nutter, when he may have been a cold and calculating killer instead, fully cognizant of what he was doing, for whatever motive, and performing with malice and forethought. That's scarier than the idea of even a latent jihadi convert, and better grist for the mills of those who push gun control. The concept that someone who appears relatively normal, or even a 'nice guy', might be a mass murderer hiding behind a thin veil of civility does more to bolster regulating the equipment than the operator in the minds of the hoplophobe, because, as they would frame the argument, 'you never know when they are going to lose it'--a fallacious argument which presumes that is an inevitable event and one which could neither be anticipated nor prevented by means other than banning items.
I am ever careful of how this is being portrayed, and perhaps overly sensitive to subtle messaging which could be used by anti-RKBA folks who definitely have their own agenda.
I'm still waiting to see what the official results are.