It’s a productive use of time. You put the time in, you get the product, and it appeals more to our primal sense because it’s a concrete thing, food, so different from a symbolic paycheck.
It’s a way of nurturing something weak, and seeing it through to completion. It pays you back, so there’s a clear reward. It’s using the brain and hands to win through challenges and overcome obstacles. The satisfaction is real.
Plus, the stuff I grow is waaaaay better than what you can buy in a supermarket. As a person who appreciates flavor, I dig (heh! dig!) that I get to have Really Good Food for much less money. I get to share with my friends, even, and they tell me how good it is and how amazing I am to be able to make food out of dirt.
But I don’t make food out of dirt. I just help dirt become food.