It's not as ominous as a lot of people are making it sound - some of these are put together on Grindr or the other apps, in which one or two "organizers" seek out users to come to a person's house for the express purpose of doing this.

There are other types too - my ex always used to get invited. It was usually up in the hills at a nice house and filled with "Influencers" and Instagram "Models" and is more often just a house party with a "back room" with low light, heavy bass, and lots of cushioned surfaces... get enough gay boys drinking in that type of space and the rest takes care of itself...

As for the invites - it's like any social network, there are a few young guys he knows who know LOTS of other gays... whoever threw these parties generally starts off by just selecting two or three of these networkers... and they handle the rest.