Not nazis any more, but that's how they got their start. They took the best submarines and technology the third Reich had been creating and went to Anarctica to establish a "shangrila", for the Furher at first, but now it's just them and their descendants and i don't think Nazism is their ideology really.
I think they just want to keep humanity in check. They don't want the majority to have access to the technology they have, such as zero point energy, anti-gravity and force fields and control of the most destructive forces in nature. They want to control those various related technologies and by doing this they hold onto power. They already defeated Admiral Bird and the entire American navy/airforce back at operation high-jump. They do need some human civilizations, but they don't need that many of us. I believe they are at the heart of ideas of earth being over populated and de-pop etc. ideas which seemed explode in popular consciousness after WW2.