Everyone must to learn a new language but in fact some people can't use a new language that they leraned.
Because It not easy to learn a new language.First of all,It's hard to understand the other language.
You must to learn new thing such as vocabulary,grammar,speaking and others.
Secondly,Many people don't have enough time to listen to quality materials, read something or speak with someone.
Motivation to learn a language is important but many people don't have it.