A trillion dollars seems like enough money to solve almost anything. We could end world hunger, wipe out medical debt, shrink the federal deficit and still have plenty left over. So when people talk about Elon Musk’s potential trillion-dollar fortune, or the wealth of billionaires more broadly, it’s natural to ask: Why don't we simply tax the rich and use the money to fix our country’s biggest problems?

Host Megan McArdle argues that while taxing billionaires may sound morally obvious, billionaire wealth is often a stock of assets rather than a flow of spendable income — and that distinction makes wealth taxes far more complicated than they appear.

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