Is EA a community of elites?

Almost entirely. EA in London is very much targeted at middle-class, cosmopolitan young people. The majority of people I meet at those events have incomes in the 70th to 100th percentiles for the UK, despite being very young. They're generally well-travelled and usually come from a middle-class background. AFAIK, they exclusively voted 'remain.' ... What are the other signals of being an elite? I can probably find them in EA London.

"Coastal elite" brings to mind often mostly white, politically progressive people from well-to-do backgrounds. Most EAs are white and liberal, and I know a lot of them have gone to elite colleges or top universities. Demographically, they're similar. There are aspects of EA characterized as elitist, but I can't think of much else that comes to mind that makes EA clearly the same as the "coastal elite" stereotype. At least, while people may have anecdotes, I can't think of any more data from the EA community that's directly relevant.