The chemsex epidemic: what does it all mean?

I've been living in London for almost 4 years now and a lot of people feel that this city is sort of like a "ground zero" for the chemsex epidemic affecting gay men around the western hemisphere. And it is true: there are guys throwing sex parties pretty much everyday, drug dealers are a dime a dozen and everyone knows at least one person who has died from a GHB overdose. Crystal meth, which is almost exclusively a gay party drug here, as opposed to in the US, has become such a huge problem that there are now Crystal Meth Anonymous reunions every single day around the city and you won't find one straight person there. Is this epidemic, mostly related to big cities, just a natural consequence of this isolated digital society we are all a part of or is there something else behind it?