For the same reason that you don't want to earn the exact minimum you need to survive. You want more/better. So does the person selling the widget; so why charg

For the same reason that you don't want to earn the exact minimum you need to survive. You want more/better. So does the person selling the widget; so why charge the absolute minimum for their widget if they can get more for it? That extra money goes towards their "more/better".