That's true in a very short term sense.

Over the long term you can either find some freelancing hours or get a job that offers a different expectation of worked hours and a different amount of pay.

So if you're out of balance you can fix it to do more of the job you want and have more leisure hours too. Or less of the job you don't want.

I concluded the same as caymanjim. I’m a firm believer in “Your spare time is only worth money if you’d otherwise be making money.” I’m not paid hourly, so the opportunity cost of my spare time is $0, and like many tech companies, mine forbids freelancing/moonlighting. The math works out to favor DIY in my case but it’s obviously not for everyone.

If I had a job where more hours directly translated into more money, 1. I would drop DIY projects and 2. I would probably become a workaholic.

Okay, but considering that it could save you a huge amount of time overall, next time you're looking for a job consider searching harder for one that has paid overtime opportunities. (But not enough to enable workaholism.)