The "caveman brain" explanation for overspending is catchy, but it’s bad psychology and oversimplified financial analysis. Human survival didn't just depend on consuming when food was available; it depended on preserving, storing, and planning for winter.

Paying off a high-rate mortgage is a guaranteed return. The market's return isn't. Here's what the “don't pay it off” advice leaves out, and why it fails exactly when you need it most.