I think what's been pointed out to you (maybe you've misunderstood) is that it's not really possible to use the national median income to determine 'class' in any real sense.No -- everything that's been "pointed out" in this sub-thread thus far seems to conflate household with individual income figures. Which is of course a non-starter, basic logic-wise. So that's where about 80% of the noise in this thread seems to come from.
The other 20% comes from a hidden circularity: In that people are now basically saying that "median incomes in a city that has become affordable only to the upper-middle, and higher classes in very recent years, are uh, you know, middle class for that city." Which you can buy into, if you want. But it completely circumnavigates the question of whether things haven't drastically changed in the city in the past 20 years -- when it actually was much more of middle class city than it is now.
But then again, if one has no recollection of the former SF at all -- like, fairly stated, your average tech worker filing into the city, these days -- then I suppose that kind reasoning might make a lot of sense.
(Parenthetically: I'll acknowledge that there's some jitter between "median income" and "middle class," even restricted to a particular geographic area. But compared to the disconnect that started this whole sub-thread -- someone basically saying that tech worker salaries are "middle class"; and other people using personal and household income figures interchangably -- it's fairly negligible).