do we need to buy what they sell and why we cudnt buy what we want if we pay for it?

when we want something , we enter to a shop and ask what we want. but salesman try to sell what we dont want by neglecting what we want.
is it marketting?
then why we pay for it if we select what we never want and dont like to use.
they controls the market by selling what they could get more profit. they never think about the quality of the items and what is the request of the customer. Y V CUDNT BUY AMD , instead of INTEL if WE PAY FOR IT?