Some people have a very strong and very strange sense of entitlement. They think that if they want something, they should have it, even if it belongs to someone else. This sense of entitlement is strengthened if they offer something in return. They will offer all sorts of justifications.
An example of this is a woman who comes into my store several times a week. We sell coffee at my store and have sweeteners, flavored creamers, flavored syrups, etc. that people can put in their coffee. Some people take one or two extra, and we don't care about this. However, this lady stuffs several handfuls of hazelnut flavored creamer into a bag. She gets very angry at anyone who says anything about it, because she offers to pay for it, and starts acting very aggressive and talking about people treating her like she's stealing. Well, frankly, she is stealing, because we don't have a way to charge her for it. We have an option in the computer to charge people for empty cups ($ .29) but she takes a lot more than $ .29 worth of creamer. I don't know why people act this way, this is just another example of the same kind of behavior.