Introduction to Esperanto:
Lesson 12

As I said, ist could mean a profession or a hobby. If you speak Esperanto, your hobby is Esperanto, so you can add this ist to say an Esperanto speaker or a person who has Esperanto as their hobby, or, as a direct English loanword from Esperanto states, an Esperantist. How would you say:

I am Esperantist.

Answer: Mi estas esperantisto.
Not correct. Please try again.