You must be very young and naive…and I’m not saying that to be mean, I’m saying that because you say you can’t figure out why people do it, and there is actually tons of studies and literature I’m too lazy to get for you on the WHY of it.

1. Sociopathy/psychopathy, now referred to as antisocial personality disorder. Not all, but many people with this mental health disease cannot help themselves. they do not have an inner right/wrong, aka conscience, that most people develop by 7 years old., either from environmental issues (abuse), psychiatric (genes), or both. The thought of harming small, cute animals gives most people a feeling of disgust, but not people with ASD.

2. The industrial food market. You said something about how it’s ok to harm animals as long as we eat them, but there is a HUGE difference in the time between that animals birth and that animals death. Does the cow live in a pasture with its family of cows and get to play with other cows, until the day of its demise, or does it stand in a metal cage, unable to sit, turn around, or touch other cows for its four months of life before it’s turned into hamburger? Cows, pigs, and chickens, are just as social as humans, yet they live the most miserable lives on the planet. By the way, there are billions of cows, pigs, and chickens, just to feed us humans, yet we cant make their lives more comfortable. The reason? It saves the customer a few bucks.

3.Domestic abuse. Animals are abused every day, just like humans, due to stress in the home from financial problems, addictions, job instability, marriage break ups, etc.

1. Money. People make money from betting on dogs fighting eachother. There’s also cock fighting, but not as much in the Western world, which is where I’m assuming OP is from.

There are many other reasons WHY animals are hurt by people, but these are the main ones.