Only one of the two reasons I put forward came down to violence and that's just reality. Humanity is the product of 3-4 billion years of evolution and most of that time has been an extremely violent struggle for survival and advancement. That is what we are. We live in a paper-thin veneer of sophistication and civility while we are comfortable and our bellies are full, but every last one of us is still an animal. We're dangerous animals too and all it takes is a tiny bit of hopelessness and fewer than a dozen missed meals for that to become evident.

You might not be sympathetic to your fellow animals, but you can bet that if a bunch of them frightened, angry, and hungry start circling because they see you as all that stands between them and survival they won't be very sympathetic to you either.

We already make a number of concessions to preserve a polite society. Keeping your fellow animals fed and making sure they have a chance to advance (something to work for) is a small price for security and stability because otherwise those things are impossible.

You can think of it as ransom, but I prefer to think of it as an investment in and routine maintenance of society itself and ultimately we all benefit and see returns on that investment.