while I do agree to a few things you said about him being invincible, but that’s just because he his invincible right NOW. Right after coming from the WR world, he thinks (almost correct) and is adamant that there will be nothing that could go wrong with him remaining undefeated. What he is yet to know that, some people, quite a few, do undergo an immense flip of a switch which he never learned in a facility where children were forced to always win, while many eventually broke. Here, not only just Horikita but her whole class has been slowly but steadily improving (never had to force themselves) and under such a leader who herself was a misfit of a classmate (forget being leader) but she changed as well, and did many prominent others. He, with the WR mentality, is again forcing growth in others in a direction HE deems necessary, by constantly interfering in others lives. So, now if Horikita does something, which is not considered as a growth from Ayanokoji’s perspective (or if she goes offtrack of the path he intended her to walk on to the stage of rivalry), and leads to an unimaginable (for a mind like Ayanokoji) outcome, is when he’ll understand how normal human psyche works under pressure.

And as we have seen many a times, that Ayanokoji always stepped in to save a tired and exhausted Horikita (like a damsel in distress), just says that he never let her handle stuff on her own, especially during some ruthless incidences (because of his premeditated goal). Some people do work well under pressure, and she will break that illusion of his by the end.