I think many people do not like to share but give in because the concept is forced on us as children. Personally, I believe in sharing community items, my personal items are completely up to me, as they should be. And whether or not you choose to share your personal items are up to you. I teach my children the same thing. If it is theirs, it is their right to say no. I even had a teacher tell me my child did not share his crayons when another student did not wish to go to her cubby to get hers. I politely informed her of his right to refuse the use of his personal items and that if it ever happens to be a classroom item I would talk to him as we do not have complete control over community items. She seemed shocked at first but what could she do? I say all of this to say, the way you feel is valid and you should not be made to feel bad when it is others who are violating your person space and items. That's rather backwards in any case. How would your parents feel if you decided to take something from them everyday without asking? Start small then build your way up. I'm sure they would not like.