Your three categories are a bit too simple. I'm not a native english speaker, I learned it at school and I use it every day at work. But I'm not fluent after 9 years of studies.

I'm from the esperantists crowd for one year now. I'm more fluent in esperanto than in english after just one year.

I have no ridiculous dogmatic reason to refuse to learn english. But the problem is quite simple : english is not an international language. It's very hard to learn, past the basis which are quite easy. Maybe some readings will give some more clues : "These Terrans Are Real Masochists".