That's the point of DRM-free ebooks though, isn't it? You download them and keep them safe so if the provider decides to cut access to your account, you remain in possession of the goods.
So the correct advice would be to avoid anyone buying DRM-encumbered digital property - the same as RMS has been making for who knows how long!
It's safer to assume that Amazon is always acting in bad faith and search to purchase your DRM free e-books from other vendors. There's plenty of other options out there besides Amazon
> There's plenty of other options out there besides Amazon
Often not in my experience. Abe and B&N.
If by Abe, you mean Abe Books, they're a subsidiary of Amazon.
I believe Baen sells some DRM free sci fi books, but it's a smaller catalog.
Pretty sure all of Baen's books are DRM free, and they offer virtually every ebook format around. They even used to include CDs with their hardbacks that would would include a huge subset of their collection. But they aren't a retailer, they're a publisher, so you're only getting the titles they publish.
Bookshop, Kobo, Google Play Books
https://bookshop.org/info/ebooks
https://www.prnewswire.com/news-releases/bookshoporg-launche...