Originally copyright was like 15 years and if the thing was really good for you then you could Apply for a second 15 year term.

30 years is a long time to get a monopoly over something. As a human being, 30 years is a significant part of your entire lifetime. From birth to 30 years you have your entire childhood, many people go to and finish college, get married, have kids, achieve a degree of professional success. Another 30 years from that moment, many people are at the end of their lives. They're retiring, some who smoked or did other things are dying of old people diseases.

I believe strongly enough that 15 years is a reasonable copyright term that my book, the graysonian ethic, which I published in 2021, has a note on the legal page releasing it to the public domain 15 years from the first date of publishing, and in jurisdictions where you can't do that, it's licensed under the creative Commons zero license

If I want to own the rights to another book, I can write another book. If I can't make back the money that I spent writing and publishing it in 15 years, then that's a me problem, not a society problem the police can help enforce.

The famous song Happy Birthday left copyright only a couple years ago, and not because it timed out. The song which was written in the era of my great grandparents only lost protection from the largest state in history because after a hundred years no one could keep track of who owned it anymore.