There are second order effects to firing people. Even if I'm doing a great job and enjoying my work, I'm going to get stressed out if I see 10% of my coworkers

There are second order effects to firing people. Even if I'm doing a great job and enjoying my work, I'm going to get stressed out if I see 10% of my coworkers get fired every performance review cycle. Sure it would be nice if people who don't carry their weight were replaced but in any profession where productivity is non-objective, that's scary.