Never underestimate the power of human stupidity.

The remark warns against assuming that bad outcomes require sophisticated villains or complex causes; ordinary ignorance, carelessness, and herd thinking can generate enormous real-world effects. “Power” here is ironic: stupidity is not merely a private failing but a force that scales—through institutions, mass movements, and cascading mistakes—often overwhelming careful planning. The quote’s bite comes from its inversion of a common bias: people tend to overestimate competence and rationality in others, especially in large systems. Read in a Heinlein-esque key, it also functions as a skeptical check on technocratic confidence, reminding readers that human limitations persist even in advanced societies.