Possession is what you literally currently use, I am talking about property things that you do not currently use but still decide over. So the house you live in is in your possession (and also your property) but the 100 others you own are in your property not in your possession.
So nobody should ever be able to take the car you use even if yours is better than mine, or even if i dont have one. But nobody should be able to keep people from using anything they dont use themselves.
does that make sense?
regading selfishness - well currently they are, you are right, I would agree with you there
However just like a tiger in a small cage in a zoo does show unusual behaviour that deviates from its healthy behaviour in the wild. So do we humans under the conditions of lack of freedom show behaviour that is dysfunctional that would not be displayed would we live under freedom. Selfishness at least in that sense is a consequnce of our current conditions. However I do not believe human beings have to be angles before we can stop fencing of most of the world to most of the people.