It's not a matter of $1. In that case obviously your example is clear but what if you taxed that billionaire so much that he decided, "why bother" and he stoppe

It's not a matter of $1. In that case obviously your example is clear but what if you taxed that billionaire so much that he decided, "why bother" and he stopped investing, building firms and simply decided to live a life of ease in Mexico? The net utility in that case with the job losses and movement of capital it entails would be negative. Now take a look at the policies on the table. Bernie's medicare for all has a projected cost of 2.5 trillion dollars annually. If we taxed everyone who makes 1 million or more a year at 100% we would have about 1.5 trillion in receipts. It just isn't possible.