Factory farming IS killing for pleasure.

Livestock animals are killed for their meat. Something close to 80 billion mostly chickens, pigs, and cows, all of whom have been shown in lab experiments to be surprisingly aware, intelligent, and social. The vast majority of these animals also spend most of their lives in a living hell.

Why are they killed? It is not because it is nutritionally necessary to do so. It would be vastly more efficient to use land and resources to grow crops for human consumption than for livestock and their feed. Doing so would vastly increase the amount of available food supply, drastically reduce emissions, and reduce the suffering of hundreds of billions of living, feeling creatures (trillions over just the next 15-20 years).

They are killed because humans have a gustatory and cultural preference to eat meat. Although meat is often healthy, western diets especially often over-include it, and meat is not nutritionally essential for health.

I am not advocating for literally all human beings to become vegetarian or vegan with no exceptions ever. In fact, the use of some amount of livestock is necessary for maximally sustainable food systems. However, we could drastically (something around 95% globally, maybe more) reduce the amount of meat we consume and ensure that livestock are treated humanely, and it would be objectively better in the long run for humanity and for the planet.