a little overtime. Husband / wife both consulting in Silicon valley = $600K. Can't do that in San Diego. $1.8M house looks cheap for a couple making $600K a year.
That's 3 years * $600K = $1.8M. With taxes , etc it takes 6 years to pay it off. That is why houses cost $1.8M in SV and $700K in SD. Wife usually can't find good paying work in SD.