Examine the following perspective on markets. use this source to answer the following question:

i suspect ignorance about economics leads many to believe that when two people exchange goods and money, one wins and the other loses. if rich capitalists profit, the poor and the weak suffer. that's a myth. how many times have you paid $1 for a cup of coffee and after the clerk said, " you," you responded, " you"? there's a wealth of economics wisdom in the weird double -you moment. why does it happen? because you want the coffee more than the buck, and the store wants the buck more than the coffee. both of you win.

--john stossel, real clear politics. com, "the double -you moment", may 30, 2007

question: how can making a purchase benefit the buyer and the seller?