I also own a car for which I have almost none of the skills to meaningfully maintain and repair, but frequently exercise my right to contract a third party to do that work for me.

The same is true for software, and I benefit even if I'm not the one paying for the work myself. The modern internet would look very different if KHTML hadn't been a GPL/LGPL project and Apple had been allowed to hold their changes in WebKit as a proprietary secret, and the same for Chrome/Blink. Companies can be users too, and the virality ensures that every user sees the benefits.