VMs, containers and "it'll just work"
VMs and containers are the new frontier of things to bite you, I suspect. Chucking stuff into a VM, then regarding it as vital - now you've got another 10GB or whatever to snapshot and backup regularly.
VMs as cattle not pets - now you've got the problem of knowing *which* VM. Chucking it into the cloud and adding S3 storage or equivalent - did you remember to specify and pay for backup of that???
Creating an ephemeral VM - easy - I can do it 20 times a day. Maintaining a VM ...
And that's before you decide to base your ecosystem on Docker or similar: "I can't be bothered to build locally, I'll just pull down the latest from Dockerhub, sight unseen ... it'll be fine."
Likewise depending on GitHub repositories to be there ...
if you *are* relying on VMs - document the process for rebuilding them, go through and do that once in a while: archive the metadata in version control. For the stuff you care about, archive *all* the software that you need and build in SPDX or similar so that you know which bits depend on which, not just for your VM but also for software bill of materials ...