Dude didn't seem all that crazy in the first video. I know there's a such thing as keeping the inner rage tucked inside (as was proven here), but still. I'd be more worried if he was exhibiting noticeable anger in a teeth-gnashing, foaming-at-the-mouth sort of way as opposed to how calm he was in the video posted in the OP. He seemed deeply depressed at worst and I've known a couple of people in my life that were just the same (not necessarily for the same reason) and they didn't embark on a killing spree.
As for why he didn't use his money to rent out some prostitutes... eh, it's probably because it just feels more legitimate if you get the poontang the normal way instead of having to pay for it. Not that I have any moral qualms about or anything, but speaking for myself, I can't see ever having to resort to paying money for sex. Plus, 99.9% of prostitutes in real life aren't what you would call physically desirable. I guess you might get a fairly decent one if you rented her out from a fancy escort service (and he certainly had the money to do that), but even then, refer to my previous point.