What follows is a long answer to a short question, but it may be needed to provide a perspective. To gain an insight into the underlying motivations in human behavior, it is useful to examine a predominant theory of our evolution as a species. In the early stages of our existence, we survived as hunter-gatherers clustered in small tribes of 20 or 30 people. In these tribes, we had to compete for sexual partners, i.e., mating privileges and precedence. Those who were seen as having superior skills or physicality were granted higher status in the group and were more able than the others to obtain mating privileges and reproduce.
As the tribes expanded in size, the quest for status became even more challenging as the pool of talent increased. Those who didn’t strive for mating privileges were gradually winnowed out and their DNA disappeared from the gene pool. Those who participated most strongly in their quest for status and mating privilege continued to strive to build their intellectual and physical skills and their DNA continued to survive through reproduction. When two tribes entered into conflict, the more capable tribe prevailed and their DNA was subsequently passed to the next generation.
The description above is a simplified version of one theory of the evolution of human intelligence. It suggests that our unrelenting quest for status in our various groups is “hardwired” in our DNA. We all seek to be recognized and respected. This is most evident among teenagers who revere “popularity” as the measure of self-worth.
With such a high premium on status within our groups, we all seek to win the respect of our fellow tribal members through our accomplishments. For some it’s our physical appearance, for others it’s our wealth, and for many it’s our intelligence for which we seek recognition. Some people promote their physical appearance by showing “selfies” on social media. Others showcase their intelligence with educational credentials from prestigious universities, while still others flaunt their homes, yachts and jewellery.
Others attempt to demonstrate their intelligence through pontification or bragging about their IQ. This is easier than acquiring respect through intellectual accomplishment and that’s why its so prevalent. In some cases, those who self-promote feel that those around them are unaware of their capabilities and they seek to achieve higher status by raising awareness of their abilities. In other cases, they wish to achieve a higher status than their accomplishments would justify. Those who have significant intellectual accomplishments don’t need to brag; the achievements speak for themselves. On the other hand, those who self-promote often do more damage to their status in the group because such self-assertion treads upon the other members’ needs for recognition.