Try as we might, IQs don't actually follow a bell curve. There are many more on the high and low ends than would be expected by looking at the curvature in the middle. Whether this is a measurement error or something else, we don't know.
Also, because of the unique position of the USA in the world (and especially places like Silicon Valley, Cambridge, Pasadena, New York) an awful lot of the right hand side of the bell curve for nations like China, India, Russia, etc. are currently living here, and often working for tech companies.
Additionally, when you do happen to get extremely brilliant people excited and working on the same thing as you in the same organization, the effects are magical. I've experienced nothing else like it.
Finally, when you're in Silicon Valley, you get the sense that there are maybe a couple thousand serious players who, if you look close, are directly involved in or are supporting most of the major efforts. It is a small world -- it seems like it's about two degrees of separation, give or take. You really get the sense that the right kind of people are the crucial ingredient that fires the whole engine of innovation here.
IQ is probably one of the less important characteristics in most positions in most companies. But it's still an ok measure for something important.
But much better to have people who are not merely good intellectual generalists (high 'g') but who are actually alarmingly good at the actual things you need to do in your company. There are as many times more of these as there are distinct things to do.
The value is defined by a bell curve.
Most IQ tests can't even measure above 155 or so, anyway, and they obviously can't measure below 0. So it's a little silly to talk about them being normally distributed.
The IQ test was invented by Alfred Binet as a way of identifying people who were having trouble in school because they were mentally slow. For this he came up with a large number of different questions that exercised the brain in various ways, and figured out how well an average kid would do. When he gave the test to a real kid he would take their performance and figure out a "mental age" that they performed at. Their intelligence quotient was then defined as 100 * (mental age) / (physical age).
The development of IQ tests aimed at adults which are defined based on a bell curve was a later innovation. The name was kept simply because it was then well-known.
That is, hearing,"You're so smart," so many times, from teachers, other students, coworkers, bosses, etc., cultivates a sense of elitism and a shock when something is actually difficult.
You're also bound by the same emotions as most other people. If you're a particularly aggressive or irritable person, imagine being surrounded by people who keep making mistakes because they're stupid. If you turn it outward, you're impatient at best and a bully at worst. If you turn it inward, you're stressed out, anxious, and depressed.
All of that said, being a professional programmer was the most satisfying thing I've done. Unfortunately, I moved on precisely because of the above paragraph -- I had managers I felt were particularly dim.
My thoughts all stemmed from the idea that compliments make people worse at what they do. At BEST they make the person continue at the same speed with a boost of moral. Imho.