If you're considering learning Esperanto, you should learn Chinese or Spanish instead
Whats your standard for "proficiency" here? After 50 hours, you're not going to have a very extensive vocabulary.
> studies show faster French acquisition after first learning Esperanto than learning French the whole time.
Which studies? If you mean those listed at https://en.wikipedia.org/wiki/Propaedeutic_value_of_Esperant... then they don't actually support that conclusion. Some more details on one of those studies in particular: https://news.ycombinator.com/item?id=14848019
By the way the second link is a critique of a single study, and it makes a pretty wild claim: "To see whether previous study of Esperanto would assist children in the subsequent learning of East-Asian languages (particularly Japanese)."
The claim that Eo helps French acquisition is much better supported from the links in the wikipedia article, considering the more similar grammars and vocabulary.
I don't doubt that pre-existing knowledge of Esperanto helps with learning French due to the large number of cognates, but it's implausible it helps so much that you get "faster French acquisition after first learning Esperanto than learning French the whole time". Cognates would at best allow you to learn Esperanto + French in the same time it takes to learn French alone, but Esperanto isn't 100% Romance-based, so even that is unlikely.
but it's implausible it helps so much that you get "faster French acquisition after first learning Esperanto than learning French the whole time"
I'm not convinced that it's true, but it surely is plausible; the other side of "can't trust the pattern" is that you can't easily see the pattern. Learning arithmetic then calculus seems better than trying to learn both at the same time; learning an instrument first then playing in an orchestra would be better than trying to join an orchestra and play with them while learning to play an instrument at all. People recommend beginners start with Python rather than 3D engine development in C++, or work on a model of an engine before they take a helicopter apart, right? Why not "learn European grammar rules in simple patterns" then "use that knowledge to climb faster through native languages which aren't so simple where the patterns are less clear"?
The only compelling argument I see is the one you mentioned about using Esperanto as a quick path to, say, French. However, if we use your Spanish numbers, it'd need to reduce Spanish acquisition time from 500 hours down to at most 450 in order for it to be a net gain. Personally, as someone who's studied Spanish as a second language, I just can't imagine it would have helped me going through Esperanto first.
But if you want a fast path to learning a foreign language (which plugs you into a meta language learning community), then Esperanto is very interesting.
Research is fairly promising for French, doesn't look like it helps as much with spanish, or at least nobody's done research on it: https://en.wikipedia.org/wiki/Propaedeutic_value_of_Esperant...
Anecdotally it works well for french because you're secretly learning French word roots, and it builds confidence in the process of language learning.
What I have in mind is the fact that French distinguishes between the vowels /ɔ/ and /o/, and between /ɛ/ and /e/. When learning new words, foreigners must get this distinction down right, it is key to having a decent accent in French, and in some cases avoiding misunderstandings. Yet when French roots were used in Esperanto, those vowels were leveled as just /o/ and /e/, respectively. That means that the learner does not learn the right French vowels from the start, and is likely to continue using in French the /o/ learned from Esperanto when the vowel is actually /ɔ/ etc.
In modern language teaching, it is considered vital to avoid pronunciation mistakes from the very start, because otherwise they become too firmly rooted to get rid of later.
Anecdotally I don't think my French is worse off because I learned Esperanto first, (nor any of the other languages I learned). If anything, learning more languages makes me more aware of the importance of pronunciation as a meta-learning aspect of languages.
It's not like those French roots aren't completely mangled by English learners anyways, words like "-ion" in "situation" and "conversation". But you learn just like any other learner.
It's a stretch to say every one of them would want to chat with you and you with them, but by the time you get to native languages with a million speakers, isn't that plenty? Is there any significant advantage in Mandarin having a billion native speakers over German having 83 million or Czech having 10 million, or generally trying to max(number_of_speakers) as a useful metric already orders of magnitude above the number you could reasonably interact with in a lifetime?
If learning Esperanto really solved the same problem that learning, say, Spanish or Mandarin would solve,
What problem are you saying that learning Mandarin solves?
With Spanish, say, I gain an immediately practical language that I can use weekly if not daily right here in the US. It gives me unprecedented access to the people and culture of Mexico, Spain, and much of the entire continent of South America. I gain access to a vast body of original literature, music, and media in Spanish that isn’t just a translation but unique to the language. These are the sorts of things solved by learning a language like Spanish.
Yes, definitely.
Dunbar's number is around 150, as long as the number of speakers is sufficient that there's a good chance of finding 500 to talk to in a lifetime, and 500 books or films of interest to consume in a lifetime, more than that seems no benefit. That is, 100 people is not enough - but somewhere in the region of tens or hundreds of thousands seems easily enough for a boundary.
"There are a billion people, therefore learn this language" is even less convincing as a reason to learn something; it's popular, so you should do it".
And since you're so hell-bent against learning Mandarin, go learn German. It won't be a complete and utter waste of time, unlike learning Esperanto.
Your hating on something which doesn't affect you, then refusing to explain your position is way more of a waste of time.
I took two years of Spanish in high school and gained more or less nothing from it. I decided one day as an adult I wanted to learn Spanish, and within a few months I could hold (very basic) conversations in Spanish.
What did I do? Well, I probably did what you did with Esperanto. I started reading extensive passages in untranslated Spanish even when I didn't know the language, looking up any word or conjugation I couldn't remember. I more or less ignored grammar, except when I just couldn't figure out why something would be said one way instead of some other way. That quickly sent me down some interesting rabbit holes that even native speakers struggled to fully explain, but as a result I rapidly got to the point of being able to form reasonably complicated sentences. I started listening to stuff in Spanish. Any time I was about to ask someone a simple question in English, I'd ask myself, "so how would I ask this in Spanish instead?" I obsessed over pronunciation, and even though I'll never perfect it I'm much better than I ever was in high school.
For what it's worth, my primary tool in all of this was just LingQ.
If you're a polyglot who wants to learn two dozen languages, then go for it, but don't prioritize Esperanto over Klingon or Elvish.
"Don't prioritize Esperanto over Klingon" is trolling.
If you're considering learning anything for fun or interest, then learn the thing which you find fun or interesting, not the thing which internet people tell you that you "should" based on something so completely irrelevant as how popular it is. Keeping up with the Jones's is a mistake, not a desirable way to live.