Esperanto is a hobby language for upper-middle class people in developed countries. It isn't anyone's "own language".
I wonder what gave you such an impression of Esperanto. My personal experience of Esperanto is quite different.
I started to casually self-learn Esperanto about one year ago as my second foreign language apart from English. After about half a year, I was confident enough to join online Esperanto communities and it gave me a surprisingly much more diverse experience than any community I had encountered on the Internet.
For example, in an online chat group, active users mainly come from US, South America, and Russia. As an person from East Asia, there is little chance for me to get in touch with the latter two groups otherwise. And there are often new users from South America who speak only Spanish and Esperanto.
I myself do not identify as a upper-middle class person, and I don't know enough to assess other Esperanto speakers' class status.
The impression of Esperanto speakers being upper-middle class may come from the fact people learn Esperanto as a hobby. But people not in the upper-middle class can have other hobbies, why is Esperanto different? It doesn't come with the many benefits that people may expect from learning a "practical" language, but it takes significantly less effort. I'd say it's about as hard as learning a new instrument. So it is not that exclusive to only upper-middle class people.
After one year of casual learning, I am now able to contribute to the Common Voice project in Esperanto (175 recordings and 123 validations) and I actually use it as a source of learning material.
Of course, it takes time to fluently "read out" the words, and in practice, it's much easier if you just know the word and pull the pronunciation from your memory.
For the Common Voice project, there are usually two or three words in a batch of five sentences that I don't know. And there are unfamiliar places and names, since most of the text come from Wikipedia. In such case, I'll take my time to use the spelling to infer the correct pronunciation and practice it several times, until I can put it into the sentence. Then I'll record. And I know it must be correct.
If I am not sure about the meaning of the new word (you can usually guess from etymology or word formation), I look it up in the dictionary and learn a new word.
Esperanto was designed to be easy to learn. It isn't an elite pursuit in the way you suggest, because its community isn't gatekept. I personally have met people of all social classes who have been interested in it.
It was also never meant to be a first language, it is an auxiliary language. It is possible for an English speaker to have a conversation with a Mandarin speaker with no intermediary if both know the (comparatively easy to learn) Esperanto. Its original purpose wasn't trivial either: it was created to stop groups without a common language in the same city (Warsaw, I think?) fighting, created on the basis that they'd stop doing so if only they could speak a common language.
Think of it as JVM bytecode for people.
And that's how it's played out. Nearly every developed nation teaches English as a second language or is a native population of English speakers. The universal language is English. The JVM bytecode for people is English.
What are you telling me? That I need to drop English?
Certainly you will find people learning other languages for trade depending on the region, but even in East Asia, as you say, English is taught in China, Japanese, Korea. In Singapore English is the language everyone learns (and is taught in). In Vietnam the primary foreign language taught is English. In the Philippines one of its official languages is English. Argentina teaches English in elementary school. In Brazil students from grade 6 have to learn a language, which is usually English. In Venezuela English is taught from age 5.
So what exactly do I have to tell them?