I think he means that wealth, once taxed, is owned by the government. If I have $100, and the government takes 5%, I only have $95 left the next year, and so on. One could theoretically be taxed to the poorhouse, whereas income is only taxed once in hand. Some assets grow over time and some don't, and many assets have over inflated valuations that make taxing them questionable, not to mention the fact that for a lot of entrepreneurs, wealth is often illiquid. These reasons make wealth taxes unappealing to me.