為什麽有人買或投資３million的ＵＮＩＴ ，４＋million 的apartment?

看到domain上一新聞:
"His agency has sold some expensive apartments in the past couple of months,
including a $4.15 million apartment on Cremorne Point and a $3 million three-
bedroom unit in Mosman."

我是工薪人，弄不明白為什麽有人買或投資３million的unit，4＋million
的apartment?

哪位幫解解。