Film Theory: The Evil Mastermind You Didn't Notice In Interstellar
1. The Brand Vs. Mann Metaphor
If you're still not entirely sold on the idea, consider this metaphor based on the names of two very important characters in the film. The head of NASA is called Dr. Brand. He's selling a brand - an abstract concept, an idea of trust for people to buy into and keep pouring resources into. He is a ruthless individual who will lie and manipulate to serve what he perceives is the greater purpose.
The other guy, who is also hailed as a hero for most of the film is called Dr. Mann - man as in human being. Dr. Mann is seen as a genius, "the best of us". He buys into the concept Brand sells him and embraces it. He falls for the lure. But when he's out there on the deserted planet on his own, he realises he'd gotten more than he'd bargained for.
In his own words, he says he never expected the planet he went to to not be the one with promise for life. When he realises the full gravity of what's going on, and what the really important things in life are, he gets into a frenzied state and tries to return, but it's too late for him.
It's striking symbolism for the constant struggle between commercialism and the individual that plays out in real life, and what might well be the theme for the secret hidden subplot in the film you never noticed!