High iq's are self eliminating in the gene pool. See Big Bang theory.
at the present time, in our culture, that is probably true, but it is far from universally true.
High functioning and successful individuals in a society are highly attractive mate material. I don't know if you remember "Mrs Merton" interviewing [IMO] ugly, little, middle aged, magician Paul Daniel's blonde bombshell of a young wife?
So Tell me, what first attracted you to bald, multi millionaire Paul Daniels?
It is also important to remember that high functioning in a society and measured IQ are not completely correlated, I don't mean this to offend academics, who are pretty clearly going to score very highly on an IQ test, but arguably, they are no where near as high functioning in society as entrepreneurs.
If the characteristics which lead to high functioning were not heritable, and were not selected for, then they would not have evolved. Hans-Herman Hoppe (philosopher and economist), gives a very good discussion of this in his "history and society" lectures which are available as free MP3 downloads. Hoppe, actually believes that the start of the industrial revolution required a reaching a threshold of a sufficeint proportion of the population above a certain IQ, so that they could adapt and emulate the work of the really intelligent polymaths.That happened around the end of the 18th century, as chance would have it, in western Europe, but could equally have begun in Northern Asia (China, Japan, Korea etc).