IQ is a relatively recent construct.

My father (b. 1913) was one of the children chosen to calibrate the Stanford Binet IQ test after it moved from Europe to Stanford University.

Having a high IQ didn’t make much difference for an alcoholic manic depressive attorney who could insult you in English, French, German, and Arabic.

He became an embezzler who lost everything and ended up dying in my one-year-old daughter’s bedroom after his last wife threw him out.

A few days before he died, he seemed to confess to murdering his first wife.

IQ may predict other things than it was designed for.