[Mr. Mojo]

It all started with 'students' in '79, and it'll all end with 'students' in '03. I guess older folks don't have the time - most have jobs - or the energy for revolution.

[kms61]

They're old enough to know how to go about doing these kinds of things, but still young enough to think they're immortal.

Same reason most soldiers are in that age group. As an old Drill Sergeant once observed, after age 25 you can turn a man into a soldier, but you can't turn him into a GOOD soldier (clearly an exaggeration, but there's also clearly an element of truth to it).