The issue you identify is a good reason why our system of government, which places an elected, term-limited civilian as the commander of the military, is extremely clever. We end up with an effective military, but have a counterbalance to a military acting as a hammer constantly looking for nails.

The people involved are certainly imperfect (and some are more imperfect than others), but we're always just a few years away from a course correction if the electorate sees fit.