А, еще Малфой вступил в ПС по необходимости, после тяжкого провала отца, грозящего семье эцихом, а Снейп мог при желании спокойно откосить.

“You’ve picked the losing side, Potter! I warned you! I told you, you ought to choose your company more carefully, remember? When we met on the train, first day at Hogwarts? I told you not to hang around with riff-raff like this!” He jerked his head at Ron and Hermione. “Too late now, Potter! They’ll be the first to go, now the Dark Lord’s back! Mudbloods and Muggle-lovers first! Well — second — Diggory was the f —”