Reading is decidedly not niche in the US. Books (across all formats) are a huuuge market. They're roughly 2/3rds the size of the entire videogaming industry in this country, by revenue. The total annual revenue of the US book publishing industry is greater than YouTube's (but just barely).
except a huge portion of the reading market is from libraries and other free sources of content. Few people buy every single book they read new.
It's a flat-out monopoly. Amazon has a strangehold on the market. If you only had to compete on the hardware, then you'd see competitors. But you need to compete with the entire market ecosystem, which is very hard.
It's like the mobile phone industry, except instead of two unassailable players there's only a single one.
I understand it that they would not release any ink devices that fragment their product lineup beyond iPhone and iPad.
However, Apple‘s lack of action in providing quality reading experiences that reduce eyestrain and effectively Compete means that everyone has to deal with Amazon’s garbage.
I hate to say it but I think reading is a niche market. Not enough people do it, a lot more people want to watch YouTube then read Cormac McCarthy.