Maybe all the motivation needed is I Own All These Guns And I Would Like To Use Them

[stopbush]

Just as logical a reason as any other.

[SharonAnn]

1. Same reason a male dog licks his balls. Because he can.

[Hortensis]

2. No. A great deal of anger and hate are ingredients. And even then,

experts say many people seriously fantasize about murder and mass murder, even to the point of enjoying planning, and enjoying possessing murder weapons, but only a few do the first and a tiniest fraction the second.

I did wonder if a nearby open-air concert gathering 50,000 people below those high rises presented an opportunity that trigger the great leap from fantasy to action. Perhaps with some other event(s) stoking the rage.

Btw, reportedly, it's common enough that, unless you're a hermit, someone has probably enjoyed fantasizing about violently attacking you, rape, murder, torture. All that's needed is some offense, real or imaginary, taken by a person carrying around a lot of rage.

[Applan]

3. Agree

Absolutely agree this could be a logical reason. I feel the same way about my many cameras.

[Dark n Stormy Knight]

4. Probably not the only reason, but you know the one about the solution to every problem

to a guy holding a hammer.