To be certain in an uncertain world
We are creatures of habit. We seek patterns that feel familiar, because familiarity is comfortable. In a brain hard-wired for survival, we fear the unknown. When a thing is known, we can assess it, classify it, determine its ability to help or harm us. But the unknown always holds the possibility of being harmful, and so often, we would rather seek something knowingly harmful than anything unknown. Better the devil you know.