Sociolinguistics 8, Exercise 3: counting Esperanto speakers

Range reported: the article says usage figures are difficult to establish;
estimates of second-language speakers run from about 30,000 to 2 million
(Sidney Culbert around 2 million; Amri Wandel above 2 million; Svend Vendelbo
30,000-180,000). Two estimates put the number of Esperantists at around
100,000.

Two reasons it is hard to be sure, from the article: (1) the estimates differ
widely between researchers; (2) its native-speaker figures are inconsistent
(about 1,000 in 2022 in the infobox, about 2,000 in the lead). The article does
not say why the estimates differ; any reason beyond these two is my inference
(for example, what counts as "speaking" the language).

What it tells you (my reading): a community with no state, census or official
status has no agreed count, so the figure depends on definition and method.

Source: Wikipedia, Esperanto (first 100,000 characters).