Short LLL, NNN or CCC or one word Domains of value normally have an original owner/registrant, likely from 1990's. That person might have resold it or it has sold many times to other speculators. The aftermarket is that second sale and beyond.
Secondary market is most usual though, just like second hand or used cars. Sure, some people "Hand register names" say in a new industry like Drones, Weed, or Crypto. The vast majority never sell, and I have seen 1000's drop this past year, great entertainment to see some of them. A domain is either used as a real website for years and never expires, or a company goes out of business and let's the name expire.
But in the vast majority if you study this market most all domains are registered many years in speculation of aftermarket resale- parked for traffic or pointed on a secondary after-marketplaces like Afternic, SEDO, Undeveloped, etc. for resale. Hopefully that answers it.