There's entire classes of people who base their employment centrally around an occupation that enables their worst vices. I'd wager there's a group of people who have no interest in becoming a teacher but put corporal punishment on the table and suddenly they're interested.

Tenuous at best in many school systems where it's typically not teachers that apply corporal punishment but headmasters.

The notion that people train to be teachers followed by spending ~10 years in the system holding out for the chance to be a headmaster just so that they can beat people is a stretch.

Bound to be one or two, but there are surely better paths for a sadist - prison guard, et al.