IQ can have its ebbs and flows when you add emotion. Some very smart people do very stupid things when emotion is in the mix. Its called the momentary FUIQ and it can make all the difference. Forty years of intelligent actions can be wiped out by one second of emotion.
It could be something as simple as a vegetable garden or marrying the right person.
Or maybe going to a psychiatrist to find out what's wrong, how to dispatch their demons, killing them, and living happily ever after.
Or maybe figuring out what it will take to stay sober and managing to do it day after day for a lifetime.
On the other hand, how smart is a high achiever with a testing IQ of a zillion who has to take drugs for situational depression and is in his fifth unsuccessful marriage?