the.com/opinion
the cheapest thing to have and the most expensive to change.
means a belief or judgment held without complete proof — what you think is true or good, as opposed to what is demonstrably so.
from From Latin opinio, 'a belief or conjecture,' built on the verb opinari, 'to think, suppose, imagine.' It reached English through Old French opinion in the medieval centuries. The root carries a quiet honesty often forgotten: it never meant fact, only what one supposes — a guess dressed in confidence.
backfire effectContradicting evidence often strengthens a false belief instead.
roman originFrom opinari, meaning to suppose or conjecture.
crowd echoPeople adopt views to match groups before facts.
changing mindsAsking someone to explain often softens their certainty.