Yeah land value taxes are cool, but ultimately taxes are just a bandaid solution to rampant inequality. As long as billionaires keep their vast economic (and therefore political) power through control of the means of production, they have the power to undermine any attempt to tax their wealth away. Which is why we need a fundamental reorganization of the economy that places the power in the hands of the people. Otherwise known as socialism :)
Except billionaires take advantage of a loophole whereby they can take out loans using stock as collateral, instead of selling the stock, meaning they pay no capital gains.