I use AA and buy books. Typically I may start a series on AA epubs then buy the books. Sometimes authors take money directly (patreon, straight donations, etc) which is how I would rather pay them than pay the publisher for them to only get a small cut.
Are libraries unethical to use? You can go to your library and read books without paying for them.
> I would rather pay them than pay the publisher for them to only get a small cut.
Publishers aren't just stealing money that should go to authors. We can debate percentages and such, but buying a book also pays the editors (who any author will tell you are just as important to a book as they are), the typesetters, the designers, etc.
I just this week bought a book I first read from AA. Though I got it from a second hand bookshop, so I guess that was unethical, lol.
But you must understand you are a minority. Most people don't do this, they will get something for free and fiercely defend this right to get things for free.
Libraries aren't unethical, because they're just letting you borrow stock of books. There's practical limits on how it scales, and any impatient users might just buy the book. Once you can infinitely duplicate a work, it's not borrowing.