Technology

I wonder how much of this stuff may still be around on harddrives somewhere.

Probably quite a lot!

Just as an example, I'm a part of an art and writing focused community that's been around off-and-on since the late 90s. Typically each member has/had their own website. So a few years ago when we went from an "off" phase back to "on" again, a major project became reconstructing the stuff that used to be on Geocities, the various smaller platforms of the 90s and 00s, and ISP-provided webhosting. And obviuously it's hard to judge how much stuff we don't remember and therefore don't know we're missing, but well over half of what we have reconstructed has come from "I found my external hard drive from 2006 and it had X, Y and Z on it!" I personally had ~3000 files sitting on my NAS, which I had moved off my own hard drive at some point, but had been unwilling to delete, so I just dumped it into long-term storage. Four years into the reconstruction project, we still occasionally find files we thought were lost forever, usually when someone's found an old hard drive in a box in their attic/basement. The found content often was created by someone else, but downloaded and archived by the hard drive owner.

Although this is representative of just one community, given how apparently common it was for people to download offline copies of websites they liked, it could well be that large swathes of the old internet are sitting on people's hard drives, waiting to be rediscovered.