One of my favorite sayings.

Although stupidity is relative:
Like Scott Adams from Dilbert says:
Everyone is an idiot, not just the people with low SAT scores. The only differences among us is that we're idiots about different things at different times. No matter how smart you are, you spend much of your day being an idiot.

Psychologically people like stories, and it is simply a better story to explain events as being orchestrated by some evil supervillain who did it on purpose.

And it feels so random, so people don't really want to admit that what is happening to them is just caused by an accumulation of small decisions made by people who at the time thought it made sense to act a certain way but in the aggregate leads to a rather stupid/ negative outcome...

I work in safety and it is a constant struggle to lead people away from simplified stories that seem to explain what happened but are no better than conspiracy theories. Systems thinking is still quite young and relatively unknown even in supposedly sophisticated fields like accident investigations....