A 2003 study found that on the Web, about one link out of every 200 broke each week, suggesting a half-life of 138 weeks. This rate was largely confirmed by a 2016–2017 study of links in Yahoo! Directory (which had stopped updating in 2014 after 21 years of development) that found the half-life of the directory's links to be two years.One might have thought that academic journals were a relatively stable part of the Web, but research showed that their references decayed too, just somewhat less rapidly. A 2013 study found a half-life of 9.3 years. See my 2015 post The Evanescent Web.
I expect you have noticed the latest outbreak of blockchain-enabled insanity, Non-Fungible Tokens (NFTs). Someone "paying $69M for a JPEG" or $560K for a New York Times column attracted a lot of attention. Follow me below the fold for the connection between NFTs, "link rot" and Web archiving.