Not everyone can consistently write books that get popular. Most authors only have a single book or series get popular and the rest of their books do not sell anywhere near as well.
Most authors have zero big hits. But authors that get one hit are more likely to get future hits.
Most people have to work until retirement age. If you happen to get a big hit that earns you enough money to retire at age 28, then congratulations, you're one of the lucky few. But society doesn't owe you the right to make a lifetime worth of money off of a single book. You can work until retirement age like everyone else.
Also, long copyright terms only affects retirement age for a very small percentage of authors. Most authors aren't well known, have no big hits, and each of their books gets most of its sales in its first few years. These authors have to work their whole life regardless. Authors with a really big hit, like J.K. Rowling, have enough money to retire after that one book, regardless of whether copyright is only 20 years or longer. It only makes the difference for those authors who have a small hit that won't quite earn enough to retire in 20 years, but will earn enough over 40-60 years. That's rare. Books usually earn the vast majority of their profits in those first 20 years.
That doesn't justify giving them lifetime government enforced monopolies. If they want to keep getting paid, they should have to keep creating new works. Anything else is rent seeking. Having to give them monopolies at all is bad enough but the current state of copyright is completely unacceptable.
Also, their children are owed exactly nothing by society. At most they should be able to inherit still valid copyrights with no change to their durations. Heirs getting a completely new two decade monopoly just so they could "benefit" is absurd and intolerable.
It's "real" because it exists in the real world. It's naturally scarce as a result since two bodies cannot occupy the same space at the same time. There's only so much land available.
It's a completely different matter compared to imaginary artificially scarce cultural property which boils down to ownership of unique numbers. That's what's ridiculous.
