I think for some, this is the last chance to become the owner of the shortest domain. If there are new domain zones with similar domains, the prices for renewal are high. Example: "At the beginning of January 2020, the Registry for .PS (Palestine), the Palestinian Nation Internet Naming Authority (PNINA), made available a number of single character .PS domain names." (https://www.namepros.com/threads/ps-joins-the-single-character-domain-name-club.1174981/)