Every book is not "accessible", when it's not even opened and willfully ignored of existing.
There is:
- https://lernu.net
- [https://esperanto12.net/en](Esperanto in 12 days)
- [https://www.amazon.com/Complete-Esperanto-Learn-write-understand/dp/1473669189](Complete Esperanto)
- [https://en.duolingo.com/course/eo/en/Learn-Esperanto](Duolingo Esperanto)
There are languages to which it's less accessible, but from the bigger ones, it's quiet accessible.
But if people don't open their eyes they don't see the forest in which they are standing.
What for a pile of crap of an opinion. Most languages can be described as "nobody" uses it. When you are outside of the top 10 languages in the world, then any language is a harder way to use it. You could move to the country or region where it's then spoken or maybe find the community in your city which speaks such a language.
Esperanto can be also found like that. There are people who speak it and also there are regular events where people can meet up.