The purpose of copyright is to promote science and arts, not to make money.
The purpose of patents is to promote (edit: scientific research).
Giving someone money for the book they wrote for the rest of their life plus some time is all about money.
(In theory. The practice, as with most things, gets complicated.)
The compromise has diminishing returns for providing protections and affordances on longer time scales, and 30 years is really pushing it.
Also I hope he's doing fine with his client list https://sedlik.com/getinfo.htm
It is pretty clearly about promoting those things via economic incentives, by giving inventors and authors a limited monopoly.