"Random sample of Internet links" is going to include a lot of absolute garbage.
If we're talking about news sites, or commentary, or blogs, or magazines, or newspapers, or other publishers, the number of dead links will be far higher. Those are the types of sites that are likely to fail, be acquired, get migrated, or become paywalled.
I worked as a technology journalist for years starting in the late 90s. I did a lot of freelance work as well, and almost nothing survives online. There were media brands that were shut down, content migrated to another site, the CMS was migrated from Drupal to Wordpress to something else, there were two or three acquisitions, and so on. Last week, I checked some articles that I worked on between 3 and 10 years ago and they were either 404s or paywalled.
When I left one of the higher-profile pubs in the aftermath of the 2008 financial crisis, I knew my articles wouldn't last even though they were migrated to a sister publication. I made PDF copies of every single one. I still have them in a folder somewhere, not sure what to do with them.
My personal blogs are still up, but even those will die at some point.