Somebody wants what you or I have. I want what I have and want to be myself. No one else.

 It could be anyone wanting anything.

Something they think they lack and need.

They want it and some people think they can steal other peoples things or wear their clothes or mimic them and somehow turn into that person. It can't happen. 

You are you and have what you have. Personal idiosyncrasies and habits. Choices. Shape. Size. Mind. Body. Material things. Ambitions. Instincts. Goals. Upbringing. 

All unique to each one of us.