Why should you learn English as a second language?

It is an international language, spoken as the main language in many countries and also recognised in many other countries. Being able to speak it will help you if you travel a lot or deal with people from other countries that don't speak your language. It is also the international language for many things, like for pilots. It is always useful to have a language that many people around the world will understand, and English is one of those languages.