There are plenty of question asking Which Programming Language Should I Learn? but I have not found an answer yet to the question what really motivates people to learn a specific new language?.

There are the people who think they should learn a new language every year for educational purpose. How do they decide on the languages to be learned?

Then I guess there are people who learn a new language because people around them told it is a fun language and they can build nice things with it.

Of course if the current job requires it people would learn a new language but I think if the language seems to have a potential to earn money (e.g. There are plenty of jobs in Java or ObjectiveC can be used to write apps for the iPhone and make money).

So why are you learning a new language or why have you learned the languages you know?