Hmm. Good word, and close. But (at least in my English understanding) it doesn't include the ignorance of past action.

A boy who trades the family cow to a wandering peddler for magic beans is credulous. But a boy who buys the magic beans a 10th time from the the same scamp who is broadly known to also sell sawdust flour and moldy bread is an extra level of foolishness.

Extending Musk the benefit of the doubt required that one willfully ignore his history of deceit. That was (and is) an error. Cf. Rumsfeld and Iraq.