But this is the way things are, it's the 'deal'. The witches of the Order are dedicated to ensuring that Ectoplasts are given a fair shake in the magic world (which isn't their world). This includes making sure the Ectoplasts don't go hungry. No one is forcing any of the students to stay at the Academy, they can leave if they don't like it. And it's not like the witches of the Order are just giving... In exchange for their dedication, the witches of the Order get something others don't. One thing is a unusually long life, the second is they stop aging around age 25 and the third is, they will be disease free the whole time. And all that without magic, just Ectoplast know-how. So it's not a terrible trade. That and most witches of the Order will be more capable than most when it comes to natural magic, because of their close relationship with the Ectoplasts.
That and, the sex is fantastic! Go sex!