Depending on the job, you can also do it better yourself than what you can reasonably pay for.

I built a custom shelf for my closet. It'd have costed me an arm and a leg to have someone else do that, even with a tech worker's salary.

I also built a custom walk-in closet. It took me a day, saved me over 2k and I got a better quality closet out of it. (You find find built yourself a walk-in-closet kits that are easy to assemble, it really isn't that hard, just don't get the home depot level quality ones.)

It definitely depends on the job. Enjoyment is certainly a factor too.