> Why does gchat, snapchat, whatsapp, fb messenger exist if AIM had been fulfilling the need of the market?

gchat & fb messenger are backed by huge companies trying to sew up the communications of a large community for the purposes of selling marketing services. The need they were created to fill is a corporate need, not a popular one.

Whatsapp was primarily popular because it made it cheap to text on your phone. I don't know the history of snapchat, never used it.