> an older book is a much safer bet if you want to maximize the value of your limited time
I 100% disagree with that. Value is highly subjective. I've read a lot of the books that are considered as "the most important books from the western hemisphere" and let me tell you, most of it is garbage. It's just a classic because back in the day it was novel and exciting, nothing else like it. You can have a good time with both, modern and old books. It's about your selection process, not the age of the book.
Reading has multiple purposes. Entertainment and education, most importantly. So I read books depending on the goal I want to achieve.
PS: if you read the commercial garbage from reading lists and what's new, you'll have a bad time, granted. As everybody can write a book nowadays, quality is harder to find tho.
But yes, of course some modern books will end up standing the test of time as well. But it's hard to judge that a priori without actually reading the book yourself.
You will spend a finite amount of time reading in your life. If you read Dark Matter now, that could for example mean that you will never end up reading Dune, or The Count of Monte-Cristo. If you're gonna sit down and read, an older book is a much safer bet if you want to maximize the value of your limited time.
Still, modern books can sometimes offer other qualities that simply don't exist in older books. Sci-Fi is a great example of that, where scienctific developments affect the writing deeply. So (unfortunately) in certain cases you might have to gamble on a newer book. But I try to avoid that.