I put earphones in but don't play music because all I want to do is listen to people's conversations.
Why do you enjoy spying on other people's conversations?
Because I like to know what other people talk about. It's like a hobby and it's interesting and funny to me.
These people are  probably having these conversations with an expectation of some degree of privacy.  You're violating that expectation by deceiving them and being nosy.
Spying on people makes me feel so powerful though!
It may make you feel powerful, but you are being very rude by eavesdropping on other people. I don't think you would like it if people listened in on your own conversations. In the future, you should try to mind your own business when out in public.