Obviously, the kinds of unrealized gains that are a problem aren’t $250k that someone uses for collateral on a mortgage for a house they plan to live in. The problems are the millions or billions in unrealized gains that someone might use to get a $10 million loan from the bank that they then use to lobby the government to open up new loopholes in the tax code.

Taxing wealth and/or unrealized gains is tricky to do right, but not doing it at all is even trickier. If you let the ultra rich just keep getting richer, they’ll continue to use that wealth to control the political process to make themselves richer and more powerful. Obscene levels of wealth inequality and democracy can’t coexist.