I've been teaching for years and here are a few things to consider.

1. Lecture material takes about 10x the length of the lecture to prepare the first time and it may not even be good. A 1 hour lecture therefore, is minimum 10 hours of work.
2. Material also sucks the first time, maybe the second third and fourth time, too. You need lots of reps to make it good and you need intelligent feedback from students to improve it. Revising is not as easy as it sounds and often takes as much time as making the lecture material.
3. Believe it or not, it's very hard to find motivated students. Lots of people say they want to learn only to doomscroll Instagram during class time. This is probably the most demotivating thing for a teacher as all your efforts goes essentially for nothing.

This is why it doesn't work to offer classes for free. The students don't have enough skin in the game, the lecturers don't have the incentive to make good material and it just becomes another failed education initiative like the many that are already out there.

Honestly, you want someone to hold your hand through learning Bitcoin without paying for it. It's not going to work for you or them. Go buy one of the many books that exist already and learn that way instead of trying to make something happen for free.