Blunder 1: war. We dropped a nuclear bomb before we ever made a nuclear power plant. Nuclear became inextricably linked with sickness and death instead of power and prosperity.
Blunder 2: broken heuristic risk assessment. Radiation is scary because it's "spooky" - it's undetectable, and it kills you in a nasty, body-horror kind of way - a long time after exposure. (Although many environmental toxins also fit this bill and aren't so "spooky", so I'm not sure what's going on there). Fossil fuels just aren't "spooky" in the same way, even though the numbers show them as far more dangerous. Chernobyl is enough to put people off nuclear entirely, but even a hundred Chernobyls would not be as bad as the environmental damage wrought by the carbon industry. A bold claim? We're in the middle of a global mass extinction. A hundred Chernobyls wouldn't be a blip in Earth's biodiversity. Even Chernobyl itself is practically a wildlife sanctuary now.
Blunder 3: Status quo bias. Sure, fossil fuels are terrible in many ways. But better the devil you know!