Some people gossip because it makes them feel important. They know something about someone that no one else knows. The excitement of sharing this kind of information is short-lived and it won't take long before they are no longer seen as a trusted "friend" once it comes back to the original person. So, the cycle becomes more intense--the gossiper must find people who will divulge their innermost secrets quickly (usually people who are used to being taken advantage of and are desperate for attention) and then they move on to the next person.
It is a sad way to live because all their relationships end up being superficial and transient. The choice to gossip will end up leaving the person very lonely and alone once people figure out their true intent.