IQ is about processing speed, not processing quality. If you're operating outside of your competence with limited awareness and inaccurate contextual assumptions you can be super-smart and still make incredibly stupid decisions.
That’s not true-processing speed is just one component of IQ. Some people can have below average processing speed but be in the gifted range in other IQ components. (e.g. on WISC-V, high GAI but low PSI). It is actually reasonably common among people who are gifted but also have ADHD/ASD/OCD/etc
