What causes so many people to become drama magnets?

I have never been the type that fussed over events/situations out of my control. The last thing I want is a person in my life that makes their problems mine because they don't have the fortitude to make an adult decision. Last night, for instance, my schedule was accidentally double booked. I will be the first to admit that it was my fault completely for accepting 2 invitations for the same night. So maturely I ironed out the situation and my choice was that I would turn down both invitations and stay home. I did not see it fitting or proper to turn down one in order to do the other as then it would look as though I had chosen the one that seemed "more fun" or a "better deal". I did not want to put out that kind of message. So instead, my option to stay home was better and no one got hurt. Sure I was bored out of my mind, but I felt better for it. The reason I brought this up is that one of the parties in which I canceled plans with confronted me last night as to why I was not participating in her plans. My reasons are my reasons and I do not appreciate someone coming and questioning my decisions. I was not being offensive towards her, if anything I was being fair to both sets of friends. If I couldn't do something with one, then I certainly was not going to go do something with the other. It just wouldn't be right and in the long run someone would ultimately get their feelings hurt. So upon my conscious effort to be moral and make an adult decision, this individual says my logic is silly and that I should just go out with the person who asked me first (which would have been her). That would be appropriate in most cases, however it was my fault that I accidentally double booked my own schedule by accepting 2 invitations for the same night. So how does blowing off one friend to do something with another constitute doing the right thing? I was taught better than that. So I guess my question to you is, what causes so many people to become drama magnets and why is making the right decision not always considered the best decision? What are your thoughts? Thanks for reading.