Learning is not an easy task. This is a point that is often times hard for native speaker to appreciate.
Learning English and for that matter, any other language can be seen as learning a new skill for many reason. First, when a person learns a new language, it forces that person to use his or her brain in a very analytical fashion. This alone will provide a great skill as it makes a person more educated.
Second, learning English will open up opportunities for a person to work and contribute to society in many different ways. Since the United States is the largest economy in the world, there will be opportunities for great growth.
In short, learning a new language opens up new vistas for advancements.