Why is it that when popular revolutions occur, the main opponents on the ground always seem to be middle-aged men?

What is it about those men of my age group that drives them to kick some student’s head in, battering them with sticks and putting their lives on the line in defense of an evil and corrupt regime? Are the jails and torture houses similarly populated by such men in their forties and fifties who think nothing about snuffing out the idealism of youth?

Both Mubarak and Ahmadinejad used members of my cohort to quell the protestors.  Middle aged men: not wealthy, not well educated, just tough, brutal and sufficiently cynical to do whatever the incumbent regime asks of them.

It makes me feel sick that the young idealists of twenty and thirty years ago often become the shady individuals holding the batons, the guns and the pliers.