What about the millions who won't have a house to sell ? In the end, the welfare state works on altruism, all those who can will contribute something, and realistically hope that we won't get to call on it. The conundrum for governments in the next decade is an increasing proportion of the population will be over 70, so the burden of funding the tax levy will have to be met by proportionally fewer people.
If only the Casino Capitalists hadn't plundered the pension funds.