Sure. Generally because they have their actions have a negative effect on our happiness, and we value their happiness so lowly that our loss in happiness overwhelms any concerns we have about theirs. We allow the raising of animals for slaughter because it affects our happiness so positively that we ignore that we are actually killing them at the end, and placate ourselves with platitudes about them having a relatively easy life up to that point (which historically was true).

I feel this keenly, being a meat-eater myself. Affordable (and hopefully palatable) lab-grown meet can't come soon enough.

Good job, too - the insects, bacteria and fungi own the planet and we just live here.

It's still them or us, now and again, really.