If you take the average person, the situation they find themselves in at the present time, including locked in expenditure such as lease agreements/mortgages/ca

If you take the average person, the situation they find themselves in at the present time, including locked in expenditure such as lease agreements/mortgages/car loans, I agree. They have already committed to spending more than 66%. Choosing to intentionally limit your expenditure to 66% is different. In the limiting case it simply means living like you earn minimum wage whilst earning more than it. Of course, if you are at the absolute bottom of the income spectrum and have no means to change that, you are buggered. We should probably fix that.