[sponaugle]

Hobbies are almost by definition not cost optimized!

[Symbiote]

Some are, like growing your own food or backpacking.

[RealStickman_]

You'd earn more money by working overtime and buying food from the supermarket instead of spending time growing it yourself.

[Symbiote]

That depends on the food. My parents mostly grew fruit, and berries especially are very expensive at the supermarket.

The other things they grew were also equal or better to the most expensive produce at the most luxury supermarket, like tomatoes that tasted of tomato rather than the watery, red golf balls they sell in Asda.