Become More Interesting and Meet More Interesting People
If your first language is English, the second most common language in the world, and yet you’ve made the effort to learn another language rather than expecting the world to accommodate your monolingualism, then you’re a rare breed indeed. This makes you interesting. People will approach you. They’ll want to talk to you. They’ll want to know what motivated you to “bother” learning another language.
Believe me, if you’re a native English speaker who speaks two or more languages, you’ll have many more lively, engaging conversations about a variety of topics than you ever would have had otherwise.
Sure, you could spend your life getting by in English everywhere you go, but that’s boring. Be fun! Be interesting! Be multilingual!