The phrase "misguided idea" refers to a belief or thought that is not based on accurate or sensible information. It means having a mistaken or wrong understanding about something. Full definition
Far too often, misguided ideas about felines have led to the violent persecution of both cats and the people who cared for them. (cathealth.com)
That's if we don't let misguided ideas stand in our way. (educationnext.org)
It resulted in school closings, mass firings of teachers and principals, and more students in charter schools, which aggravated complaints that Ms. Anderson was catering to wealthy ideologues with misguided ideas about how to improve urban education. (nytimes.com)