It is true that a part of people sharing a piece of content through social media is based on an altruistic need to share information that the user believes is valuable to the greater community.
For the most part though, some recent research that we completed at NATIVE VML clearly demonstrated that many people share content as a way of defining their own sense of self.A need to self-define
In the same way many people choose brands because of what it says about them, a large proportion of people who spend time on social media are choosing to share content because of what it says about their own style, taste, beliefs, intelligence, or values. It is essentially a way of curating the perception of self, just as much as the way you choose your clothes in the morning.
Ultimately though this need to self-define through content is part of the reason that there is a desire for a continual stream of new content. We know that in the digital age people are starved for content, and that the accelerated production of content has meant that we have now moved from a 24-hour news cycle to a nano-second news cycle. In truth this content is not necessarily more insightful, it is simply broken up into digestible and shareable sound bites. Online personality
In the age of social media, content has become a currency that people are using to define their own self-image online. The difference between social as a currency and any normal currency, is that social currency has to be unique in order to have real value, like an up to the minute news tweet, or the content needs to have an overriding self-defining message which is stronger than its uniqueness, like supporting an anti-poaching message. The commonality between these two pieces of content is that they clearly define the sharer as a type of person or at least an aspect of the sharers personality when the content is shared.
Many brands wonder why there is not more engagement with their content, and it is simply because it holds none of these elements, it does not say anything about the people you want to engage with. There is no reason to share it because repeating it says nothing about the sharer.
So when you create content that you want people to share consider carefully the selfish aspect. How will the sharer see this content as complimenting their online personality when they share it?