There are lots of definitions of comfortable. It seems like this article uses "Similar financial resources to your neighbors'", so the number sound right to me.

I went to grad school with someone who grew up as a subsistence farmer in Nepal. He has a much different idea of comfort/luxury than I do, but still likes to buy big TVs, etc. because thats what you do here.

My definition of comfortable is being able to afford 6 acres within a 12 minute commute from work. That really limits the jobs/locations that would be comfortable for me.