I’m leaning towards decades of suppressed anxiety boiling up towards an explosion, possibly fueled by benzo and alcohol addiction, taken, ironically, to deal with anxiety. He seemed to gravitate towards risk. Making money in real estate usually means a huge amount of leverage, and casino odds are not great for customers. Not the kind of thing you typically see an accountant/auditor do. Sounds like a Falling Down scenario without the falling down, meaning the stress becomes unbearable, so he stages a blow-off event, because of a mind addled by a combo of benzos and booze. One Freeper commented that 1/5 of the dosage of a single Valium pill prescribed to Paddock was enough to get him babbling deliriously.
That's where I'm leaning as well. I think people looking for some kind of religious or political motive aren't going to find one. So far there's zero evidence this guy was ideological.
FWIW, looking at the extensive history of mass shootings in the United States, very few of them were politically or religiously motivated.
“ADULTS:
Management of Anxiety Disorders and Relief of Symptoms of Anxiety.
USUAL DAILY DOSE:
Depending upon severity of symptoms—2 mg to 10 mg, 2 to 4 times daily”
From Drugs.com