Why do farmers plant crops year-around if their only concern is to sell strawberries for a few months of the year to make living?

Thay have to eat. If the strawberry crop fails and can't be sold there has to be some backup food supply. No strawberry sales income to buy food? They have a little backup from the food grown year round. How did the settlers get by a hundred years ago. They planted a years supply of food and sold some to buy sugar, salt, and what ever they could afford. We got it easy right now. Best you get forty acres and start growing something edible.