You make way less selling things wholesale, than you do selling small amounts to a larger number of people.
If you sell to a grocery store, after you pay to grow them, then you pay to harvest them, then you pay to store them, the you pay to ship them. Then a factory pays to clean them, then to label/package them, then to store them, then to ship them to the grocery store's distribution centre. Then they pay to store them, then ship them to the grocery store. Then they pay someone to get them to the shelf, and pay someone to run the till.
If you do a "u-pick" set-up, you grow the fruit, then you pay someone to run the till.