goes to their housing costs. For instance, Nerd wallet says 28 percent of gross income is max somebody should spend on their monthly home expenditure- inclusive of principal, interest, taxes, insurance.
To your point, it could be that CBers have generally been prudent when buying homes - or they bought when homes could be had for 250-400k in many places. (We bought our house for 330 and it’s worth around 800 now. We could afford a more expensive house but at 2.25 percent mortgage rate and a pretty small house payment it would be financially crazy for us to move)