Putting on a uniform doesn't turn one into a government drone. There's no way the US military would march in tyranny against the citizenry. Even China and Russia have to use Mongol units to kill their own people. The US is about freedom, and many of the troops in the US military are there in that cause. I was for instance, keeping the Russians out of western Europe. Just ask the Poles and Czechs which side of the iron curtain they wished they were on. For some it takes a loss of freedom to realize its worth. Service to the nation also helps, because we are the nation. So, to an ex military who served the cause of freedom, service for citizenship, as in the right to vote, doesn't sound like such a bad idea. Think about it. Do the filthy rich volunteer to die in the trenches? No its those that serve the good causes they believe in. Except the Germans of course.
Or you get rich people who skate like GW Bush. Who technically did his 'service'. But it was made damned sure he was at next to no risk, and maximum comfort, while doing it.