This question should be asked on Codechef forum rather.

Still, some IITians do participate on Codeforces contests. Whether you are a topper or not, this does not affect whether you will do CP or not. It is there choice whether they want to participate or not. There is no compulsion that they need to participate. Also, there is an enormous amount of competition in IITs especially CSE and heavy workload. This could be one of the factors that they do not participate regularly. Well, they are also human beings.

Again, these people have developed great problem-solving skills already. For many of us, we do CP for fun and to build our problem-solving skills.

Are they taught something different than us lower-level college students? If so, what syllabus do they follow ?

Answer: Almost all the colleges do follow the same curriculum in India. Although, these people have some flexibility in choosing their courses of their branch.

Also, there are few people from India who seriously or passionately do CP. Many people here confuse coding interview prep with CP. That is why people in India think that many people here are doing CP. That is just ridiculous. The point is people from India who participate more are much less than the people seem to. Although, The participation from IITs and BITs is good as compared to many other colleges in India (not necessarily from CSE branch) These colleges have better coding culture as compared to other colleges in India.

Finally, as people from other colleges are not able to participate/practice regularly, same follows for them. Other commitments or things which have higher priority currently might not allow them.

I would urge you to not think about these things much and practice.

Correct your facts. Just look at that college's ( IIT-B, IIT-D in the present case) standing and google the names of the first N people to find their AIR.