It's great when as individuals we have the luxury of choosing where we work. I'm at a point in my career where I have that luxury and I use it. I'd leave a place that frustrates me enough, either in terms of mission, management, or coworkers. As a group though, a lot of us lack that choice, and even for those who do, when they step away the employer will just find someone else to deal with the crap they left behind, because funds are sustenance, we've all got to eat, and if there are spare funds to hire people, more people will keep entering the industry (it's not like other industries are exempt from this - they often have it worse).
None of this means we should give up on trying to make the world a better place, for those of us who have that ideal. We just usually will lack the leverage to do much, like almost everybody else. And if we start with the idea that we're wiser, more ethical, or the people who are uniquely situated to debug society's ills, we're starting with a significant handicap.