Then you also have those who still use unsupported Mac Pros. I know a friend who was in this dilemma and I asked why they still use it. My friend replied that it still 'just works' and switching to something else isn't worth the effort.

By then you can see why when I gave them the choice of either upgrading to the latest version of macOS + H/W upgrade or just installing either Ubuntu/Fedora/etc on a second partition in which both are long winded processes the decision was obvious and clear to them.

They didn't care about either solution and rejected both suggestions to carry on with the status quo with great reason: 'If it ain't broke, don't fix it.' So until their favourite app requires a higher version and kills their productiviy, it is enough of a reason for them to upgrade it. A full blown switch to any Linux distro would be the worst decision for my friend, especially NixOS since even with this blogpost it gives little reason why they should bother switching.