title_body: By what criteria can we say that a conlang has a functional speech community? On another question I commented that I doubted that if Lojban had a functional speech community that its purity would last very long.
  
  By what criteria can we say that a conlang has a functional speech community?
upvoted_answer: Here are some ideas, which when taken together would give a good idea whether a language has a strong functional speech community.
  
  
  If a conlang has thousands of fluent first language (L1) speakers, that would be clear evidence, but even Esperanto, the most spoken conlang, has only up to 1000 Esperanto speaking families. Ideally those L1 speakers are able to meet and speak with each other regularly.
  Even if the speakers are second language speakers, if there are so many speakers that distinct dialects have formed (without that being part of the design from the beginning) then that evidence of language change is evidence itself of healthy speech communities.
  If there is friction between speakers of the language and the language's academy or regulators then that shows the language is starting to take on a life of its own. If the language regulators have ever had to make concessions to the speakers, then that shows the speech community is healthy.