Is there any sense in these books? If you better understand crypto? Have you started to trade better?
It is very strange to ask this question. For sure, books on Bitcoin, written by those people, who have been dealing with cryptocurrencies for years, can be helpful. You do not need to buy them in the stores - just read the stuff online or download them if you use torrents. Audiobooks on cryptocurrencies are available on YouTube, and there are some podcasts devoted to this crypto.
Actually i would prefer a list of ebooks freely available, preferably in .epub format for my Linux based (Sony) ereader. The group that needs to be purchased is off limits to the people in my country, that is, unless you know of a book store that accepts bitcoin... Which Amazon clearly isn't, and i'd rather avoid the convoluted way of buying Amazon gift cards...
As for trading, he would need books on trading. Doubt understanding the coins themselves would make him any good trader, but it might convince him to hold...