The fun thing is that it doesn’t even matter how smart you are to begin with beyond a surprisingly low threshold.
If you care about being "happy"? Sure.
But plenty of things require a bit more than "a surprisingly low threshold". You're not going to be Jeff Dean (for example) if you're just "smart".
So, in response to your first comment, "it doesn't even matter how smart you are" is not accurate unless you specify the context you're referring to.