The people of Gith lost everything under the domination of the mindflayers. By the time they were able to rebel, they had lost their homes, knowledge of what home was like, understanding of what life was like before the Illithid, etc. Once they broke free they split, one side wanting to just be done with wars, etc. and one side so blinded by hate and loss they felt they were OWED everything that was ever taken from them. Both sides will kill an Illithid on sight, but the Githyanki Hunt them. They hunt them and they Take. In their minds, all the other planes were spared what happened to them because of their suffering and thus OWE them. Their leader went to hell to make a bargain and never came back. Dragons now come to aid them. Their Queen is a lich that absorbs their very lives yet they believe she exalts them to a new life. Corrupt leadership and loyalty have made them into what they are today. Something that most likely their long dead ancestors would abhor. The funny/sad thing is, if they ever actually found their homeworld, they would not recognize it. They would capture/slay the people, steal the resources, etc. In fact, they may have already done so.
Illithid are an alien parasitic race who enslave and kill any that cross paths with them. To them you are either food, raw material for reproduction, or slaves. They are (and should be) totally alien to most they encounter, their goals, morality, etc. are totally different.
