I can't imagine Anand ever playing Rb4 in any other situation except this one. Earlier on the move b5 was truly spectacular and gave Black the edge, I think this is the first time Anand gained such a dynamic initiative over Carlsen in this whole match (barring the game he won). Also Carlsen was short on time, I mean so was Anand himself but with one game left this was a now or never kind of moment. On the whole I feel that Rb4 was more of a hopeful and deliberate gamble (as in he knew what he was getting into) than an actual nervous breakdown.

This approach is what chess pedagogue, Dan Heisman, would call "hope chess." Which is in contrast to the superior approach of full calculations.

Exactly.

I am not a rated player but dabbled in chess throughout my youth. One lesson I learned that stood out is to always avoid "hope chess" (although Josh Waitzkin articulated it in a different way). Even when playing with weaker opponents, always play as if you are playing a top rated GM.

This was an unnecessary gamble. He let the fact that he had to win the game cloud his judgement.