There are workarounds that can show how smart you are without spending a lot of money attending college. For instance the card game bridge requires a pretty solid IQ just to attain a moderately high ranking. So if you are smart, putting time an energy into becoming a ranked player can send the message that you are smart without mentioning IQ directly. Moreover the top end of companies are often populated with champion bridge players who will immediately identify with you if this is your hook.
PS This example would not work for me. I was a miserable failure at bridge.
In any event, the trick is to be able to stealthily convey abilities and drive via a well written bio.