The 'boom' in high end housing came from overseas buyers, mainly Red Chinese 'businessmen'; as reported some of them are actually hotels for wealthy pregnant Chinese women coming into the U.S. to have their kids so they can claim 'citizenship'. It's a big business; they have travel agencies specifically catering to that demographic in Red China, and around the world, for that matter. I guess all the 5th columnists will get jobs chauffeuring all the wealthy Democrats in the Senate and Congress around, to make it easier for the traitors to pass on all our secrets to their heroes in Peking, at least the ones Wall Street and the big multi-nationals don't rush over to give them.
Like all markets catering to the top 1%, the customer base is small and they only buy so much; it's a very limited market size, but some people have some delusion it's endless.