Baloney hai bhai, so you should take the argument one at a time and prick holes. IIT Bombay graduating GPAs range from 5.0 to 10.0/10. IIT Bombay general category cutoffs (for JEE) range from 1-8000. Just because someone is a graduate from IIT Bombay, you can't assume that they had remarkable academics or even remarkable JEE rank. I had mentioned in two comments below the baloney comment that in IIMA, only 75 seats are available for people from IITs/NITs/BITS.
Also, you should ask your "friend", what they had to face to be able to reach a position to qualify as High school teacher.
Also, where do you think the best brains in the country are, if not at these institutions. If you chain of logic is to be followed, people who excelled enough to be GEMs at IIMA, are creme-de-la-creme. Between 1980s and 2020s, probably #seats (for the GEMs of our society) have remained the same