How to interpret China's old saying that three generations are rich and three generations are poor?

In fact, the ancient people were poor, mostly because their educational level was too low, so a large number of rich people could afford to go to private schools. Rich families hired tutors and very young people to accompany their children to study. It has caused a large number of people to be illiterate and can only do some simple things. I don't have the knowledge and mind to think about all kinds of strange things. You can only work for landlords and businessmen, or make a living as a soldier. Furthermore, I cultivate wasteland and make a living by planting. Life is simple, there is no ascending channel. As a result, the poor are getting poorer and the rich are getting richer. Nowadays, most poor people are just born in poverty, and they can still live a rich life through their own efforts. Here, Bian Xiao introduces a book about the ancient private school culture, which can be read by interested readers.