Independence is having the knowledge, skills, equipment to do it yourself if you had to - not doing something just because.
I didn't build my vapor phase reflow oven, either.
I'm trying to solve my own problems, not craft a basic piece of equipment for bragging rights; I just don't have the kind of free time to have things not work perfectly.
That works, maybe, if you're a giant of indusrtry... Hyundai doesn't have to buy ram for its cars, it can build it.
But if you're small, you can't build most of what you need, and you should not build what you can buy that's better than whaf you can build, and you may as well buy things that you can build as good unless the cost to build is much less.
Sometimes it's fun to build things instead of buying them, and that'a ok. But if your goal is to do X, you're better off spending time on X than spending time building tools you could have bought. (Unless building the tools builds requisite knowledge)
There is no bright line on the DIY spectrum between that injection molder and making your own charcoal to refine iron.
I love building machines - enough so that I never build anything with them. Maybe someday I will, but by then 15155 will have built hundreds of things.
