We cannot safely assume. It my experience, it does not take a lot of training to operate an AR-15 or a 40cal Glock. You could learn to load and fire either of these weapons in about five minutes. Nothing hard about insert magazine, pull charging handle and pull trigger. Same with Glock, substitute rack slide for charging handle. Guns are not complicated machines. They are in many ways simple. As for shooting and aiming, the worst shot in the world would cause mayhem in a crowded movie theatre.
Sometimes the simplest explanations are the correct ones. Here an evil maniac opened fire in a crowded movie theatre for the reason only the maniac knows. No conspiracies, no paramilitary training, no politics involved.
Okay, point well taken, Gusty. I would add, as many others have speculated, that the maniac could have purchased all of the equipment using a credit card (not a very “massive arsenal!”). Fireworks are easy to obtain in Wyoming.
What still troubles me, though, are the pyrotchnics and/or explosives which were rigged in his apartment. That setup has been repeatedly described by sources as being “sophisticated.” Also, the killer’s method of egress into the theater remains unexplained. An emergency exit door would be fitted with an alarm mechanism.
And sometimes they're not. Yours is every bit as much conjecture as the guys saying he was the latest in a string of Monarch Programmed disposables.