17 USC 106 gives copyright holders exclusive rights to reproduce and distribute copies; no exemption exists for downloading digital copies because you own the physical book, and fair use (17 USC 107) is unlikely to apply when commercial alternatives exist and you’re copying entire works from unauthorized distributors.

> you’re copying entire works from unauthorized distributors

Yep, this sounds like an issue. So the idea from MP3 early days of "let me download these files as a backup before I lend my CD collection to my cousin" is not a real option.