While what you say is true, I think it is a failure of generalization. A few special cases show it is possible, but what you don't mention is how extraordinary these cases are and at what time they happened and what background, including ideas, information, location, and motivation the people had.

You can very much buy an education in many places. Money from parents pays for the best universities, no, actually schools already, the best teachers, the best atmosphere/setting for learning. While some children work on a farm, rich people's children will already be learning, simply because the parents can afford it.

There are many places, where it doesn't work like in your extraordinary examples. Just because something is possible for a few, it doesn't mean, that it is generalizable and that it can be done for everyone.