You’re bad at evaluating risk

Over millions of years of evolution, our brains have become extremely efficient at responding to perceived risk. The reason why is pretty straightforward — if you were slow to detect and respond to an actual risk, you died. Therefore, you didn’t have a chance to have or raise offspring, so your “too slow” genes died with you. In the evolutionary landscape, there were plenty of different magnitudes and intensities of important-enough risks (“will that animal eat me?”, “will falling from that edge break my leg?”, “will those fast-moving waters sweep me away…