[Sambdala]

"Generally, a teacher making $100,000 teaches about 125."

Only if you count all the classes they teach every day. However, kids don't come to school for just one class a day. Each teacher gets 15 to 30 kids 8 times a day for 1/8th of the day (assuming 8 classes a day). Not that that's really the important point here...

"My point in all of this is that free is not free and that those who are willing to build courses and content at this scale need to be compensated somehow for their time."

He is getting compensated though. At $29.00 a pop. The fact that he puts free material out there will almost definitely raise his compensation, not lower it.

"More instructors, more classes"

You don't necessarily need or want this. If one teacher can teach xx,000 people in a given subject, the teaching market will start to resemble a more 'winner take most' market, allowing those who aren't as good at teaching to find use elsewhere.

It will also allow everyone to learn from the best instead of only 125 people who happen to be in the right school district.