I've somehow never believed that theory. There are tens of thousands who buy gas guzzlers, at whatever price of gas was/is. If only people were that rational, they'd stop buying them to save our planet.
You can tax cigarettes all you want, people are still gonna smoke.
Sure tens of thousands buy gas guzzlers because they can afford it / don't care. But there are also tens of thousands more that don't because they can't afford it.