Needs and wants

I am wondering why is it human never ever satisfied with what they are given and they will just keep asking things from you once you have given or compromise to their needs and wants in the past. I encounter something like this most of the time from my family but I never really thought that this would actually happen at my own university and when this happen everyone will just point finger at each other and start raising their voice when what they ask for are not like how they wanted it. When people start raising their voices arguement might just start and when there's arguement it might just make the situation during that time worse as its very hard for those people to come to an agreement. I think its better not for me to elaborate my story as this might hurt some people’s feeling so I will just end it here and hope that everything thing will just back to normal as it is before.