Bees cooperate in the hive due to instinct. I doubt many people would attribute their behavior to secret narcissistic desires seeking approval from other bees.
Altruism can exist and even be selected for without psychological motives. That said, there are plenty of people who do such things to send signals deliberately.
There's also the covert contract, which is essentially the belief that by being a "good" person the world will repay you in some way (or overlook your flaws). You can actually satisfy this psychological need by making truly anonymous gestures that are never revealed to anyone.
Beware of people who are always looking for hidden motives, they may just be projecting. ;-) And so might I.