OP was not saying anything about intelligence or claiming to be highly intelligent. It was a personal (and very interesting, IMO) anecdote on their experience with math text books.
He said that getting into IIT was more difficult than getting into Harvard, which is a pretty clear claim about the intelligence of an IIT student, and by extension, his intelligence.
The IIT graduates I've met are generally quite smart, but I've also noticed occasional arrogance which can lead them to think, say, and do irrational things, such as implying the superiority of IIT to Harvard, e.g. comparing apples to oranges.
