As in jumping from one house to another just to get a larger size. Of course I'm assuming that they don't rent their starter home. And there are other considerations such as a lower interest rate at the time of one purchase. But considering the cost to sell a house with realtor fees, loan fees, and looking at an amortization schedule, there is value in purchasing a house and staying there 30+ years. Or the main purpose of not having a mortgage when you are ready to retire.