clog

For the same reason why a lot of attractive girls are not smart or funny or creative. Now this will sound like a gladwell-esque statement but unlike him I have no stats to prove this right or wrong.

But, being attractive sometimes can cause people to not focus on trying to be smart or funny because they don't need to. In case of IITians, they are usually smarter than the average folks and all they need to or want to rely on is their intelligence. In their over reliance, they tend to ignore a lot of other qualities that make up for a successful career. The big bucket of which is Inter-personal skills and soft skills.

Now, I don't mean they fail, but rather underachieve their potential a lot of times. Granted that the entrance exam is meant to test raw intelligence but the students should have the good sense on build on their raw intelligence.

Contrast two people who do similar in their academics, one brighter than the other. The bright one scores without much effort and the other one does the same but as a result of lot of diligence and hard work i.e attending classes, being nice to the professor, participating it the class by asking questions and may be even dressing well in vivas and classroom. Now, assuming the output is usually same for both of them, the latter would be much more successful in a professional setting. The diligent one is used to being nice to professor and can do the same for his/her superiors. They focus on forming relationships, socializing and in extreme cases just plain old sucking up.

Also, doing something easily some times undermines the value of the work done, so again, the diligent ones score better. Overall, there is more sympathy towards them and they have the right 'look' and usually there are more of them as compared to the brighter ones.

On the other hand, the bright guys don't stop at being careless, some times they develop contempt for lesser able folks (sometimes their bosses) and that is a true recipe for disaster in a team setting. Part of it comes from the culture propagated at IITs. Hard working people are not often seen very kindly there even if they do well. Worse is someone trying to suck up to make up for it. If I have to draw a quadrant, this is how it would look.
Now, even though I have generalized it for IITians, I have seen enough non IITians who's over reliance on performance and complete disregard for everything else has been disastrous for them. This argument may not be valid in all the settings. More or less all the jobs need easy to average problems to be solved and hence other things become more relevant.

However, if you can get to a place where the problems are genuinely tough and there is a clear case of some people doing it clearly better than others, the 'non performance' things may become less relevant. So, for someone with this issue, choosing the right environment may be the easiest and most sustainable solution.