https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

This pattern of over-estimating competence was seen in studies of skills as diverse as reading comprehension, practicing medicine, operating a motor vehicle, and playing games such as chess or tennis. Dunning and Kruger proposed that, for a given skill, incompetent people will:

• fail to recognize their own lack of skill
• fail to recognize the extent of their inadequacy
• fail to accurately gauge skill in others
• recognize and acknowledge their own lack of skill only after they are exposed to training for that skill

Example: "We should just deport all the bad people" (not an exact quote) thinking that no one really tried that before.