The reason for this is pretty simple : They have a savior complex.
A saviour complex is when someone has the belief that they have to save people from something that's negatively affecting them. Inherently, it isn't bad, obviously. But a lot of primal creators transition into grifters after realizing how much selling courses actually pays (marcusyoung as an example).

The only good example of courses done right was jirka hrom's old skool. He wasn't doing it entirely for the money. His old skool community cost 1$ per month (eventually raised to 2$). This was to filter out low quality users.
This framework is great for cultivating a high quality large and active primal community. He even advertised it for meeting up with other primals. His new skool costs around 23$ per month. Although it has a lot of modules, it's not worth it to join. He already creates entertaining primal videos and gives out value for free.

So basically every primal creator starts off by creating a course out of a saviour complex and then either transitions into a grifter and starts maximizing revenue or they keep doing primal content and building their skool community .

The takeaway is that there isn't anything inherently wrong with the pay to access community approach. It's actually a positive when the price is low (1$ per month) in order to filter out low quality users. It's just that the majority of people who start skoolfagging eventually fall down a slippery slope of either becoming a grifter or dedicating all of their time into their skool community and becoming a slave of their own product.