Having a billion dollars is a side effect of our current system. Much more useful to focus on system level incentive than to focus on a small minority at the top.

If there's people with budgets for yacht, then there are a much larger group of people with budgets for fancy houses.

And an even larger group of people whose incentive is to see the price of their homes rise, contrary to the societal goal or providing affordable homes for everyone.

If you implement a nationwide land value tax, I believe the wealth disparity will start to disappears and there may be less billionaires, but everyone will benefit.