Just as the stock market soared in 2017, rich and famous folk bought and sold residential properties coast to coast at dizzying, previously unheard of high prices. Indeed, Taylor Swift’s $18 million acquisition of a downtown New York City townhouse and Matthew Perry’s $20 million purchase of a mansion-size condo in L.A.’s Century City — it was listed by Bachir Oueida of Douglas Elliman — barely merit a mention on any short list of the year’s top celebrity sales.