Most people are probably excited to be getting refunded for books they have already read.

Probably the refund does not account for inflation, though.

500 dollars today may not have the same purchase power of 500 dollars a few years ago.

Yes, I am always disappointed when the unexpected refunds for things I considered worthless don't account for inflation.

That's not the point of a personal library.

What if they didn't care about building a personal library, but only wanted to read a couple of good books?

Would you say going to the cinema is also a waste, because you can not keep the movie you watched?

I'm aware of the issues, I just decided it doesn't really matter. It is rare that I want to read a book twice, or that somebody wants to borrow a book from me.

Rather than wasting storage space for books, it is probably more efficient to rebuy books when I want to read them again. Or bet on ebooks.

And even once they’ve “learned their lesson” what do you propose they purchase instead? The non-DRM alternatives are often no where near as convenient, if they’re available at all.

Well having your book collection suddenly deleted is not convenient either...

So, the alternatives: 1. Buying a real/paper book 2. Pirating/illegal downloading

The best option seems doing both, you support the author by buying the real book, and download a pirated copy for convenience.

I buy physical copies. In the cases where I buy digital media, I strip the DRM. I also support DRM-free vendors, like gog.com.

You can't depend on companies to honor their agreements in perpetuity, especially when there's no direct, ongoing economic incentive to do so.

DRM-free eBooks aren't actually all that hard to find, though it varies by publisher. There are plenty of publishers who sell all of their books DRM-free. And plenty of larger platforms like Kobo tell you at the bottom whether it's a DRM-free EPUB or has Adobe DRM attached, etc.