This really boils down to cost-benefit analyses for both languages.
English:
+ Financially lucrative by opening career options
+ Access to English-language media
+ Many speakers in your age/regional cohort
+ You were probably taught it in school and have some familiarity
- On the margin, it is harder to learn
Esperanto
+ On the margin, it is easier to learn
+ Greater grammatical precision
- Nonexistent financial return
- Little/no works produced originally in language, compared to English
- Few other speakers
(Sidenote: Even if the requisite effort to learn Esperanto is much smaller, you can't just ignore the number of current speakers. I would be shocked if the collective study time for all competitive players to learn Esperanto with the exclusive purpose of more precise comms (a contested issue to begin with) is less than what is required for the non-English speakers who lack career or cultural incentive to learn to do so for TF2)
You may sincerely believe that the positives for Esperanto matter a lot. But as revealed to us from the continued incumbent status of English, people don't agree with you. You presented your case against the status quo and are seemingly offended that people have justifications for why the status quo is what it is. I'm learning a language other than English because it's good for my career, not because I think it's the Best Language or that we'd be better off if everyone spoke it. That's the main reason people learn languages--anything about its grammar or syntax is a tertiary issue to me.
AimIsADickjnkiWhile being wrong...
This guy is the exact person that you're supposedly trying to make things better for. He's telling you in no uncertain terms that he thinks your idea is unrealistic. He could have learned Esperanto, but when he ran the cost-benefit calculation, he opted for English. Rather than assume he's just not Educated enough, try to understand why he made the decision he did. Allow information from people who actually make these choices to shape your views--that's how you learn how things work.