Where did they go?

I'm sure you'll find a variety of answers. Often mid-management jobs in possibly tangentially related industries. Basically retired early, or pursued a hobby business, if they could afford to do so. In my case an industry analyst job for about ten years until I went back to marketing for a software company.

And lots of people early in their careers never got another job at the same level again.

One sysadmin I worked with ended up as a taxi driver. A core network engineer eventually retrained as a school lab technician. Two devs both spent a decade doing tech support at a call centre before bouncing out of tech altogether.

Things started picking up again around 2005-6, but for a couple of years there was nothing. Much, much worse than the Great Financial Crisis or anything that's happened since.

Yeah. I was lucky enough to connect with someone I knew in a tech job--albeit one that wasn't that great paying especially after a pay-cut at the worst of the downturn.

It eventually translated into a very good end of career job but a lot of people ended up in "would you like fries with that?" positions. I had luck but it was by no means guaranteed.

I won't disagree. A lot of people got marginal jobs--maybe associated with the industry or maybe not. I was luck enough to have a network but I knew plenty of people who just faded away.

Yep. I was lucky and lucky I had a network. Lots of people probably ended up working at Starbucks or, at least, working in at best peripherally connected occupations that paid a fraction of what they were making or what they expected to make.

Certainly, in my case, lucky as I was, it wasn't until my next job that I was really making "good" compensation a decade or so later.

There was a period when the $200K-$300K job was a given for many in development. Easy for that to vanish in a puff.