What do they gain from this type of marketing?

I’m mainly thinking about online courses in my country while writing this question. But maybe it can apply to other things as well.

I just realized that a lot of online courses particularly courses about self improvement or skill improvement follow a certain pattern: they would say something like the course is worth a large amount of money, but for some reason, maybe through some sponsor from a “celebrity” or just out of the goodness of their heart to help everyone, the course is now reduced in price, or even free. For example: “This master course’s price is 1000$, but because this famous personality in the field of self improvement is hosting it, it is now free!”

To me it’s just so redundant. You can just say “this course is free and is hosted by a famous celebrity” and it still makes no difference. But a lot of people are using this tactics so it has to be some kind of benefit to it. What do you think about it?