I disagree with your assertion since it wasn’t properly qualified. Linux is indeed a valid consumer OS but it has never been a mainstream OS on the desktop. In spite of that, it has become a mainstream consumer OS on mobile, in the form of Android.

Anyway, the original point of my reply was to highlight just how involved building a new OS from scratch is, relative to other software projects you could work on. Add to that the unlikelihood of ever seeing a pay off for the amount of resources that would need to be committed to such an endeavor, unless you are under a big tech company.