Might be useful to ask a different question: What makes people happy? It's things like relationships, satisfying work, accomplishment. (and many, many more) Then the real question emerges: How many of those happiness 'sources' are made better by intelligence? What percentage? Relationships? Seems like no. Work? Also seems like no, lots of work doesn't make use of a high IQ that people enjoy nonetheless. Accomplishmen…
Alternatively, maybe it's just that overthinking that is driving some aspect of what we call intelligence; the ability to plan and see things in complex layers.
Good amounts of happiness surely require some selective blindness.