I would guess the ones earning that much are probably in metro areas like the bay area and Seattle.

I imagine those in the Bay area are making a lot more than 50k/year, or at least there are always SV devs chiming in saying they are making 300-600k/year (the OP said 100k for a couple).

I make the equivalent of 100k USD in a tier 2 city in Scotland (a single income that is, not a couple combined). It's not outlandish for senior roles across much of the UK (with "normal" companies, not FAANG).

Yeah, dude, there's a site "Levels FYI" that gives real data. If anyone's having trouble wrapping their brains around it, just keep in mind that every business needs to send a sizable chunk of its revenue through Silicon Valley to stay competitive (via advertising, office equipment/software, apps, etc)

100k is attainable even in the middle of nowhere in the USA, but you'd probably be better off working remotely for someone for 120k+

New CS grads start off at like 120k. New boot camp grads start off at like 100k. If you're experienced, you might get up to 200k. If you're experienced and good, you can hit 300k and beyond. Once FAANG sets the standard like this, then basically everyone else needs to offer similar salaries if they want to compete for that same quality of engineer.

Assumptions, not data. Even if you assume the reader of HN is in tech firm, you can assume the "household" income average

It seems a reasonable enough assumption to me, that tech workers make more than average - so much so that I didn't feel the need to trawl for a peer reviewed data source.