Because it's pretty much essential to learn English unless you plan to spend the rest of your life in your own country, never venturing outside, never going onto the Internet except to read pages and talk to people of your native language and/or country and never taking part of any cultural elements such as movies, videogames or TV-shows unless they're dubbed in your native language (and thus losing some in the translation and limiting yourself to the stuff that's only released in your native country).
As opposed to learning, say, French, where in doing so, you'd be able to speak to a few million people worldwide, learning English will allow you to do so with billions of people worldwide.
English is pretty much essential to know these days. I was born in Vietnam and raised in Sweden, yet I speak English. I learned it mostly on my own accord, way ahead of when the Swedish school system expected me to, because I realize very early in life that learning English would make my life much easier and richer.
At age, like, 10, I could watch English TV-shows and movies (we don't dub them in Sweden unless they're kids shows) without bothering to read the subtitles (sometimes I do just to laugh at the at times bad translations), I could read books in English, I could chat with people online (I joined my first forum at age 11... 12 years ago, I was an early adopter), I read manga and watched anime and American TV shows years before they were ever released/aired in Sweden, and when abroad, I was never afraid of not being able to make myself understood as long as I went to a country that had inhabitants that were at least reasonably well-versed in English.
English is your 1st language, so you wouldn't understand how important it is to actually learn English should it not be your 1st language.
Poor Europe.
