It depends in what context we use the word hate. Lets take a look at word “value”. We can use use the word in the self serving subjective sense of worshiping the self, as in determining ones own self worth irrespective of any objective truth about the matter. You often here or see people claiming or behaving as if they are better than other people, forcing there imagined sense of grandeur on to other people. Or we can look at the word in terms of its more humbling objective connotations, as in, it is a word that refers to something objective being the cause of ones value rather than one own self determining imagination. It is in this sense where i think we begin to catch a glimpse in to what it truly and objectively means to hate ones self, that to hate God necessarily involves hating ones self, even if the person doing the hating is not conscious of it. This is because if value is objective then value is determined by something other than ones subjective sense of self. To value ones self objectively and “correctly”, is to seek the greatest objective good for ones self; as in, one must seek the very thing that will fulfill ones existential nature. As creatures of God, our fulfillment, value, and worth, is determined by God. Therefore, in this context, to truly love ones self is to seek God; and to reject God is to hate oneself, since you are rejecting the very thing that gives you true moral value, worth, and personal fulfillment. A true person, angel, or self, is one that is preserved in the eternal grace of God. Those outside of that grace have rejected their true natures. Thus one can say that the devil hates himself, his true self, the fulfillment of his nature, because if he truly loved himself he would love God with all his heart, since it is in God that he is truly a person or angel. In hell, there are no true persons or angels in the sense of what person ought to be. The kind of self love that the devil has is not love at all but a perversion of his nature, in fact a contradiction. The devil is irrational. But you might say that the devil is more intelligent then us. But in end, it seems, even super intelligent angels can be victims of a distorted sense of self pride, since to have created conscious sense self is a temptation to be selfish. Pride is the cause of hell.
Yes, its pride. Pride makes one think that he or she is God, as in, the source of ones own glory. In having a self we are tempted to be our own Gods, and since God is love, this means that some of us desire or intend to be self serving, as in, selfish. The problem with that is, our very being is a manifestation of love and exists for the sole purpose of serving love for all eternity. Some people resent the idea of that.
But like you say, these are just theories and are far from giving a full explanation as to why the devil would fight a losing battle. We cannot really know whats going on in the mind of Satan; and i don’t want to know.
Some people, however irrational it may seem, think that it is far better to rule in hell than be a slave in heaven. The devil is a practical nihilist, as in, he does not want his actions to be ruled by an all powerful God.