system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How only a few companies can sell Domain names.

How do domain names work, and how do companies like godaddy get a corner on the market? Why can't anyone just sign up for a domain name?
gpt
For the sake of doing this like an ELI5 we will focus on the .coms rather than going into detail on all of the different structures for obscure TLD (Top level domains) like .ms, .tv, ...


Essentially the companies you buy a domain from (eg Godaddy - Registrar) need to speculate on how many domains they will sell per year, and pay that number multiplied by a registration fee (7-10$) to the larger body (eg Verisign - Registry). So it takes the financial power of a large company to pay the up front cost to the registry.  
Additionally the Registrars need to follow specific rules and regulations laid out by ICANN (the regulating body of the industry) and other financial/procedural standards.

Bonus fact:  At the origin of the .com, there was only one company (Network Solutions) who was both the sole registrar, and the registry.  This was later broken up, Verisign essentially purchasing the Registry power, and allowing other companies to set up Registrar functions.


Source: Worked for a Domain registrar for a few years.