The same reason you think that they did NOT originate in India. I don't know whether they originated in India or not. But, we blindly accept whatever the west tells us. Did you examine the documents that they presented? How do we know that aeroplanes did not exist before the last 100 years? Why are we so proud to think that we are the most intelligent generation?
I am not validating their claim. I don't know. I am just invalidating your argument. You can't just say something is wrong because you can't comprehend it or you have been told that everything that is written in Sanskrit is wrong. We accept everything that the west tells us. We are like their bonded labor, "Yes Sir. Whatever you say is correct."