My plan is to bank enough money from software jobs to be financially independent at a high standard of living (I'm well on my way to that). Then afterwards, just retire and do all sorts of hobbies without trying to make them into a career or earn career-equivalent amounts of money from them.

If you're currently on that trajectory (i.e. you're able to save a large percentage of your income every year) then I'd recommend it. If not, then yeah, you might need a second career if you want to get out of development soon. My plan is not to need one.