Recent encounters with murder stories

So with any murder story, there's always a motive, a reason why the killer, uh, kills.

Sometimes it's because of an affair.

Sometimes it's a mercy killing.

Sometimes it's just revenge.

Recently though, I can't help but find that a lot of murder stories have really bad motives, maybe even terrible motives.

What is a terrible motive?

Killing people because they're insane. That's it. There's no reason, it's just because they're insane. (which, really, is the motive behind many if not all serial killers). And I guess that, when a murderer murders multiple, seemingly unrelated people, then the motive will default to "insanity."

But when you get a line like this:

"...or a culprit that gets his kicks from killing people!"

Well...really? Really? That's it? It's for kicks? Kicks? B-o-r-i-n-g.