"if you can not afford to buy it twice, you can't afford it in the first place"

An excellent maxim, which has crystallised for me why I am so reluctant to move to a bigger house, even though I would like one, and I could buy one immediately for cash plus the price I'd get for my current house. It's because I can't afford to do that twice. With an extra cost-of-a-house in the bank I might.