I really think there are two serious problems with this logic.
The first is that institutions have a culture and they do change. So if everyone believed like you and were absolutely opposed to changing things from the inside, that is a self-fulfilling prophecy. The reason I say that I agree with you more than I disagree is that 14 or so years ago when I left federal government service, I cashed out my federal pension. I did so because I had zero intention of ever working in government again. I was persuaded otherwise because I learned that there really are accountable government officials and it takes good people inside and outside to make that happen. Government is inefficient and sluggish, but in most cases, government is not evil. I also worked in the private sector and didn't see a whole lot of difference--20% of the people do 80% of the work everywhere. I still don't work for the feds and I don't think I would seriously consider it again. But the logic still stands--if you can work for a good place and do some good for the people, then the government, like any other employer, can be a good place for a decent and hard working person to work.
The other reason I have a serious problem with this thinking is that it is ad hominem. Think about it this way: one of my good friends is a police officer. He's just as digusted with law enforcement abuses and excess as any of us. The complaints you and I would have, he would agree with. And he's really really good at his job. We'd all be better off if every cop was even half as good as him. So what is he to do? He only has a few years left. Is he supposed to quit and find a new way to support his family? Even though he knows that he's doing his very best work for the people and that will leave only the incompetent people behind? Why should he feel guilty that other people suck? And why does he carry the blame for the incompetence and ineptitude of others, when he himself goes to work every day and is the change we all want in the world?
America is a very individualistic country. The allegation that any institution is "top down" and everything is carried out is just wrong. That's why good managers pretend like we're all a family or a team, because Americans don't like being told what to do. No person in any American institution exercises power this way, not even in a business where one guy owns the whole thing. It may seem like that, but if you think about it, no American institution works that way. To be that way would be unamerican. That's not how we function.