Certainly a lot of negative thoughts are based in self. That is an interesting insight. Fewer thoughts of self, fewer hindrances. All negative thoughts have the sense of self. Interesting. And so, yes, maybe it is that all negative thoughts are based in self-pity. We want, we crave, because we think we don't have enough. We have aversion because we don't want what we have. We are afraid that this person, this sense of self, won't be able to handle whatever circumstance we are facing. A sense of self. We have fear because we are afraid for this self. We have doubt because we have a huge sense of self. And, normally, we have a negative sense of self, feeling sorry for ourselves and having self-doubt. All unwholesome thoughts are probably based in a sense of self, but I don't know whether they would all be self-pity. Compassion for ourselves is the antidote to a lot of these things. Compassion and Wisdom, understanding that when we are attached to these negative thoughts, we do truly suffer.
Self-pity is, however, usually defined as feeling sorry for ourselves, feeling that our suffering is too much, and getting weighed down by our own suffering. It is hard to define it because it depends on what is present at the moment. For example, when we feel sorry for ourselves, sometimes we make our suffering bigger than it is, feeling nobody has as much suffering as me and elevating our sense of suffering. We may be weighed down by thoughts of, "Oh, it is too much." These are types of thoughts of self-pity. We may take our suffering personally, say if we are having a headache - "Oh, I have a headache. Poor me." Rather than seeing it is just a passing experience, we feel sorry for ourselves. Rather than having Compassion for ourselves, we need others to feel Compassion for us and seek attention. fThese are all manifestations of self-pity.