That’s _not_ common sense from someone owning an iPhone 6, then upgrading to the XS, not when they can purchase the XR, which would be a middle ground phone. I doubt an iPhone 6 owner would opt straight to the most expensive iPhone, not when the XR exists for a cheaper price point that offers similar functionality and capabilities.
Why not? The 6 was the top of the line phone at the time and after 3 or 4 years use I think it’s common to get the next top of the line phone.