Assuming 1 teacher making 100k teaching 20 students * 5 classes * 3 credit hour classes a semester ~= 333$ / credit hour. 128 credit hour degree ~= 43k over 4 years. And that's assuming relatively small average class size and ignoring adjuncts etc.
Yet, many schools are charging 4-10 times that much. The question becomes what are the 3+ other people doing if not teaching and can you get rid of that?
PS: And sure some professors make well over 100k and facilities are not free, but again many people even at expensive schools are pulling in less than that.
Assume a PhD student making a $35k stipend or a foreign grad student making $14/hr.
This covers a good 25%-40% of the curriculum, depending on the institution.