There’s some distinction to be made too between cruelty, and just plain apathy, dissociation, or whatever (I’m tired and struggling to word today).

When you mow down a heap of homes in Sim City you feel nothing because you’re not linking your actions to a real impact on actual people. All you have in mind is that if you do it, you’ll be able to use the space for something else that works better for you.

To some people, that’s how they view the world.

Assholes want relative gain, not absolute.

Plenty of people get joy or even sexual pleasure from watching others suffer or die. Its not common, but even one person who acts on this can cause huge amounts of harm to dozens or hundreds of others. A lot of the most fucked up crimes are the result of this sort of thing. Unfortunately, these are also exactly the sort of people badly regulated police and military also select for (IE police in the US, the military in most developing nations)

I think your assumption that personal gain being the main driving force behind everyone’s behavior is flawed. That may be true of humanity in general, but it is not true of a great many individual humans. Mental health is a multi-axis spectrum and very few of us are right in the center. There are many factors that can push people to do things against their best interests.

The book John Dies at the End has a line I’m going to have to paraphrase that says something to the effect of “cruelty is the purest display of power”, and it makes sense. You do something you know they don’t like, but for whatever reason, they’re forced to take it. Not fighting back is an implicit agreement that the cruel one has more power.

A feeling of power, a sense of pleasure by ruining it for someone. The reasons are many, and each more despicable than the other.

We’re not rational creatures. We’re basically just jumped up apes who just barely (so far) have managed to control our atavistic impulses enough to stop us from killing ourselves.

There are several options. Sometimes they overlap:

• Direct gain such as romantic opportunity from sabotaging a rival or items of value from theft. Some people are callous about the harm caused, while others rationalize it as necessary or justified.
• Retribution or justice. Most people are happy to hear that a child molester will receive abuse from other prisoners, to give an example.
• Sadism - direct satisfaction or pleasure from causing pain to others. This is unlikely to make much sense to those of us who aren’t sadists, so it may have to be enough to just know it exists.

Now consider politicians promising to harm some out group and people voting for them. It’s a combination of the first two: the politicians attempt to gain elected office by convincing people that the out group is evil or dangerous and promising to do something about it. The voters believe these cruel actions to be justice done to vicious criminals.

Some people like to know they’ve made an impact on others, that they control them and their feelings. They like the idea that they’re living rent-free in someone’s brain. Being awesome, kind, contributive, etc is one way of doing that but it takes effort. Being cruel is another, usually easier, way to do it.

Same reason people smash stuff up and spray shitty graffiti - it’s far easier to destroy than to build but both kinds of ‘work’ get noticed.

It’s ansiolotic. Like people who do drugs or have compulsive behaviors. Some people feel better after hurting others. Usually because they have been hurt themselves.

Here’s another take. I think some people would never act cruel towards their equal yet they can easily act cruel if they believe another human to be someone less than their equal.

This is why during war times it is common to develop nasty names and personas of the individual enemies.

I think it’s formed if you cope hard enough to believe in us vs them (as in believing there’s a fundamental difference between you and people you disagree with) and also tap into fear(these people aren’t just different, they want to take what you have and everything you value) then you can take pleasure in other people’s suffering. it’s disgusting and I fear most of the country is no longer capable of empathy

Its all for personal pleasure and stems from a lack of empathy. They either enjoy the feelings of power over others, or it makes them feel good and they don’t even bother thinking of others in the first place. Be it general abuse, sexual assault, or even killing and eating, cruelty is done for personal gain.

I often wonder about this myself too - especially when it comes to people being mean online. It’s absurd to me that just because I said something they disagree with, they think it gives them the green light to viciously attack me personally instead of addressing what I actually said. And often, it’s from people I haven’t even interacted with directly. I just don’t get it. I never feel the urge to be intentionally mean to someone, and I can’t imagine what these people think they’re gaining from it.

cruelty is a tool by which you enforce your will over a large population.

citizens not behaving? remove gun laws that put children at risk.

citizens not worshipping you? take away their ability to provide for their families.

citizens rebellious against you? violently capture them in public and send them to a dark hole never to be seen from again.

funny thing about cruelty is, if you must be cruel be decisive and quick. let no more suffering happen than what is needed. people who live in unnecessarily cruel environments tend to stop being afraid after awhile…and then the riots start.