First, I am not a practitioner in the book publishing industry. It may not be accurate to answer only from my experience and understanding. I hope it helps you.

Second, I don't know the profit of the book business in the past, but I know that paper books are facing a huge impact now: first, e-books are very popular now; Second, there is a lot of knowledge, information, materials, news and so on on the internet, and it is illustrated with pictures and texts; Third, the cost of accessing the Internet by mobile phone is very low, and it is very convenient to carry at any time.

Third, to sum up, my suggestions are: first, I don't know whether investing in books makes money; Second, I think the progress of science and technology has a great influence on paper books; Third, I don't recommend investing in the book business.

The above suggestions are for reference only.