I feel like it’s more a reflection of their base. Not all these politicians are stupid. Many have CVs showing very high functioning, sometimes even in academics. I think this is more about how stupid they think their base is.

Granted a lot of it is them acting outside of their expertise. Ben Carson was a good example. Definitely not a stupid guy but looney tunes crazy as a politician because he was acting outside his field.

Their are some nepo-trust-fund idiots though. Maybe it’s more like a stew of idiotic behaviors from various etiologies.