They can only consume.
I see your point, but I wouldn’t be so quick to condemn lawyers (even though I DO think there is a plague of them, and I enjoy lawyer jokes as much as anyone...) But I do know, going into court without knowledgable legal representation is like putting your head on the chopping block.
I am much more ambivalent about teachers, since it seems that there is much more indoctrination going on than teaching in many places. I don’t want to paint them with a broad brush, but we are spending a huge amount on public education, and it isn’t enough (ever) to them. I fault teacher’s unions to a large degree, and liberal legislators at all levels who always think that throwing more money at the problems in education will fix them.
Bureaucrats are also necessary, but I am willing to bet we could cut the entire federal and state governement workforce by 75-85%, and most of us would not know the difference except at the Registry of Motor Vehicles.