If you've oversimplified psychology and behavior that much there's no point asking "why" anyone would praise anyone. You had as an unstated axiom that self-int

If you've oversimplified psychology and behavior that much there's no point asking "why" anyone would praise anyone. You had as an unstated axiom that self-interested action are not praiseworthy. You still have not made an argument for that, though you have pointed out that a world composed only of self-interested action would be an unpleasant one (I agree). However, using a more realistic understanding, where actions come from a multitude of motivations, why do you consider a given action's being self-interested to exclude it from praiseworthiness?