Vaguely related, one of my biggest tax pet peeves (beyond people that don't understand marginal tax brackets at all) is the people who will cynically claim that a billionaire just donated to charity $X because they actually make more money from doing that because of the tax deduction. And it's like, no, they get to deduct it from their earned income, so they mathematically always end up with less money by donating it and deducting rather than just keeping it.