Just asking...

The more I learnrd about human 'unique' behavior, the more complex I think human is.

A few day ago, I was just thinking about human.

Why human do certain things and why do we think like this.

Then, I suddenly thought of something weird about we,

the most intelligent creature on earth do!

So I would like to ask you what is the weird thing?
The question is
What is the thing that we, human buy it and plan to throw it or sell it away?
clue : those who buy 'it' are consider the smarter people in society!

Please answer! hehehe...

can't wait if one of you can answer it correctly!