Also, most people on the planet speak multiple languages. There are even less people on the world that only speak a single language than there are English speakers. So, if anything, speaking just a single language, even if it’s English, is the abnormal thing.

That’s your opinion.

Lastly, it’s not about “feeling successful”, as you put it, but about being able to communicate with more people and being able to enjoy more things.

Like I said earlier. I don’t have any reason to learn Spanish or whatever if I only talk in English.

Languages were made to communicate with others. USA resolved that issue.