That post was at least
That post was at least marginally credible. There are numerous upper middle income types who drive Roadsters and the Model S Signatures that have been delivered so far. Think college professors or computer programmers who are true believers in EV's.
It might not be a wise choice for your money, but a lot of people can afford the payments for a $100,000 car if they prioritize that. I am aware of groups of friends and family of modest means who were on the Signature list, and some of those people had the temporary leases on Roadsters that lasted until they received their Model S.
The chance that a cluster of Tesla fanatics like that lives in the same neighborhood is higher than purely random chance. I know for certain that clusters like that exist on the scale of a town.