Argument 3: You're cooking cancer into it
Order a well-done steak around a med-school student, and you might hear about HCAs & PAHs, which are chemicals that form when meat is cooked for long periods in high, direct heat. In animal tests, these chemicals have been proven to increase the risk of certain cancers. Terrifying!
According to Cancer.gov, though, there's no concrete evidence indicating that well-done beef puts actual humans in additional danger. (If you're reading this, you are a human, probably. Or at least a Chick-fil-A cow.) More good news: doses in the animal tests were "equivalent to thousands of times the doses that a person would consume in a normal diet".
Even if HCAs & PAHs are cancerous to humans, you're probably alright unless you're eating 1,000x more well-done steak than the rest of us. Don't do that, fellow humans.