Ask any random stranger in any country on Earth what should they learn as a second language.
That’s easy, English, duh! It is the language of international commerce, of technology, of entertainment.
Unless they are already a native English speaker, then you get a blank stare. What other language gives you access to so much of the world? Mandarin? You can’t even speak to all Chinese in Mandarin! Spanish maybe? Self-fossilized French? Russian? Handy for space travel, maybe?
I think English actually has the largest vocabulary by far of any language. It is the richest language in which one can converse. It has far more nuance, in general, that other languages. Of course, in specific areas or terms that may not be true. But the broader point is that England produced the world’s most literate language. It is a gift to the human race.