Spain forced all jews to convert or to be exiled in 15th century, although they were the most succesfull bankers and merchants (perhaps because of that).
When all the gold from America arrive to Spain in the next century there were no one to use it wisely, so the Spanish Empire turn into an economic disaster.
[Edit: Heinlein died in '88 so he can't have been talking about the Soviet Union and its empire, which anyway I don't think falls into that category].