Pure joy and benefit, with no downsides.
Saying there are "too many" ebooks is like saying there are "too many" kinds of cookies. I don't stress about having too many choices for dessert; why should I stress about having too many choices for reading? In both cases, I just pick one that looks good. I don't feel any compulsion to optimize my choice.
The perfect is the enemy of the good. I've never had access to "the best books" before; only those books that happened to be available within my price range at a physical bookstore. So there's no real reason I need "best" instead of "good" now. My method of picking a book is exactly that: "Wow, that book looks interesting. I think I'll read it."
I don't need to keep records of books I've read; I know which ones they are. Nor do I need to record what I've learned from them. Either I learned it or I didn't, and what point would be served by recording it? It might be nice to have some version of Amazon's recommendation engine (after years of training it, the thing is remarkably accurate in recommending books I already own) but I didn't have that for most of my life, and I managed to pick good books, so I'm not too worried about lacking it.
I don't have to read the best book. Just an interesting one. And I don't stress about it at all.