They sell them, not usually at a bargain. They used to have vastly more SEO juice than they do now -- there is a little more intelligence going on these days from the search engines in regards to domain registration changes.

Still, lots of newspapers and magazines have great "page rank" for their domains, and they are going out of business at an extraordinary rate, being bought up, all the content pulled from Internet Archive and replaced to make them seem legit and then a couple of links installed in the footer to your favorite off-shore casino.