GEDmatch became famous and controversial overnight when, last year, investigators used it to find relatives of the Golden State Killer and track down their suspect. Until then, it was just a site where you could upload your data from a DNA testing service, like 23andme or Ancestry, and see who you might be related to. Since that happened, two genetic databases have become popular with law enforcement. FamilyTreeDNA shares data with the FBI, unless you opt out.
This is the usual dilemma users face (although this one is a lot more intimate) you share some information with a site that is very useful to you (think Facebook here too) and it is free, but the aggregation of all that user data is worth a fortune to someone (whether it be advertisers, forensics investigators, etc). It's just a matter of time until the data has that value. Hosting that data costs real money to the service provider.
The answer is quite easy and to be blunt means the service provider has to get value that exceeds their costs to provide the service. Yes some few that can afford it, or keep it small, may do it for free as an egotistic or other non-tangible reward. But this aside, they either sell your data or allow intrusive advertising, or you as the user must pay something monthly towards the service. Many users refuse to pay but want all their data kept purely private - that is like oil and water, as they don't quite mix. Eventually a service dies off if someone cannot cover it's costs.
It's worth just keeping in mind though when you register on any site and share data. The saying "what you post on the Internet is never completely private" is quite true. What I have as "private" I pay for monthly and host it myself.
#technology Genealogy Site GEDMatch Is Now Owned by a Forensics Company