English is not the easiest language to learn and yet, the Americans were able to share their language to a lot of countries. The language became widespread that it started to be used and learned by other countries. It is considered to be a universal language and people can usually communicate better with others when they also know how to speak English.
For other people, they feel that they should pride themselves for learning how to speak English because it was not easy and cheap to learn. They have spent a lot of money just to learn English. The fact that they are now able to understand and speak English gives them a sense of fulfillment.