There is an huge amount of pop entertainment convincing kids that English is the "cool" language to learn. Before it used to be just pop music and Hollywood crap. Now is YouTube, memes and software. Also, it is the language of "cool" brands from Nike to Starbucks. No other language comes close to this brainwashing.
And then there is English usefulness. It used to be the lingua-franca for just business, international relations and science. Now it is a lot more than that: it is the language of international social networks and forums such as HN and Reddit. For any kind of culture, technique or know-how someone would want to learn English. It is probably even more useful than math. In most countries, people will earn substantially more money if they know English. Hint: do you know any non-english programming language? Even those created outside of English cultures (e.g.: Python, Ruby, Lua, Coq) are written in English.
Edit: an anecdote that helps understand this. Portuguese and Spanish are "sibling languages", very similar to each other. It would make sense for people knowing one of these to learn the other, since it would be both easy and useful. However, all over Latin America or the Iberian peninsula, people put more money and effort into learning English than their other sibling language.