Why are interviewers rude?

They are themselves insecure. Don't think much and move on. It is good that they rejected you otherwise it is not a good idea to work with such uncool colleagues. Kindness is cheap, yet so rare

Because they are Indian interviewers. Try giving interviews to Europeans and you will realize the difference

Because they went through 100 more people before you who tried to scam them with fake resumes, keyword littering, proxy, dropped calls, applications by people who can’t even do basic thing, etc.
I agree that they should still be human and all that, but nobody is a saint. For every single worthy person, there are 1000 non productive fakers.

Update : I would like to add that one of the interviewers were from TCS. Coincidentally I shared this experience with a friend and she said she had a similar experience with the same company (different panel) . I am beginning to think it is more common than I had thought.

Also , I must mention that having a decade of experience myself I have been on both sides of the table, yet I haven't experienced such behaviour until recently which is why I was puzzled and asked the question here.

Omg!!! I have experienced the same!!! Some panelist’s are so rude and think they know it all. Never had the same from non indians. They are always polite ans respectful

You cannot find answer to everything in life, just give interviews and forget