The Walter Mitty stuff is in part a giant discussion on the motivations for pro-social or altruistic behavior across the social sciences.
If you want a techy book on it:
Dovidio, J. F., Piliavin, J. A., Schroeder, D. A., & Penner, L., (2006). The social psychology of prosocial behavior. Mahwah, NJ, : Lawrence Erlbaum Associates Publishers.
Also, views of aggression are useful. It is an interesting perspective to see altruism as an outcome of such processes as compared to some philosophical /theological view of the universe and humanity. The latter is sometimes immune to empirical evidence in debate.
Such an academic. Sigh.