People
Never underestimate the power of human stupidity.
— Robert Heinlein · Time Enough for Love

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The warning gives stupidity a force that people may fail to allow for. Its bluntness pushes against the comfortable assumption that others will act reasonably. Rather than offering a detailed explanation, it makes the possibility of foolish decisions sound like something with serious practical weight.
Context reviewed