Common man may think so! But, it is not.
You come to IIT to study to BECOME an expert in the technical field. So, if someone was already an expert, there was no need for him to study.
Companies usually hire people or universities recruit students based on their performance in IIT, not in the JEE. If you do well once you are in IIT, THAT is a validation of your technical superiority. Studying in IIT is not; although you have a better chance because of better facilties and faculty.
Thanks for A2A. After going through B.Tech. in IIT and Ph.D. from US, I see that life is always a struggle. You cannot sit on your past achievements. Just look at Virender Sehwag. He is my favorite cricketer. So, I wish things were different, but no one really cares for him today (anyway, not as much as they used to). So, studying in IIT is no different and you will always have to work to (im)prove yourself.