Jamie Dimon asked the question the other day, "How do you know it ends at 21 million?" followed with a few questions that had a scornful tone about the reading of code.  It's understandable that he doesn't read code - most people don't know where to begin.  I don't know if viruses, DNA, or black holes actually exist. So I rely on biologists or physicists to confirm or deny their existence.  I thought I would do Jamie Dimon a favour, look up the relevant code, and then explain it. He's a banker, so he should understand the numbers I talk about. The rest of you will have to trust me - I'm a mathematician.  I then go on to talk about the one scenario in which there isn't a 21 million cap, and explain why it is highly unlikely that it would come to pass.