Sure, but Kreia is a Sith and she TURNED away from Power. She had the galaxy at her thorat via Revan, and turned away. True power is the ability to keep the freedom to choose what you want to do, and, well, at least one Sith, Kreia, was able to choose how to do things, and was able to do what she wants to do. Kreia knows how to gain power, but she does not want it, in fact, her main goal is to fight for the freedom of the Human race from the Force, who she hates for manlipuating both the Jedi and the Sith.
Kreia is more in keeping with the ideological spirit of the Sith fighting for freedom than Darth Nihlius, who is consumed by his hunger, and Darth Sion who is consumed by his pain.
But I think this is totally offtopic. Kreia is a rare example of what you say may usually be the case. Or maybe not. If you are in power, you cannot be enslaved. The only way to make sure you are not having your face crushed by a boot...is to be the boot itself.
Horray for the Grey Jedi!
Playing Dark Sided in K2 is much more funner than it is in K1, and more rewarding too. Forget credits, you only kill for credits to gain DS in K1. In K2, you get to Mind contorl people to jump off bridges, subvert a refugee camp to get them to surrender to the Exchange (so that you can arrange a meeting with the Exchange boss), secretly off three military Generals for General Vaklu by exploiting their fears and weaknesses...Being Dark Sided is great. And the DS ending for K2 is also great, as you now take contorl of the Sith Order.
You did save the galaxy from Darth Nihlius, and you get to slowly build a Sith Order, to fight against the True Sith. Sure, teh galaxy is wrecked, but it was Revan who did it, and you could rebuild it how you will. You get to secretly run the galaxy now as a Sith Lord. But, even if the galaxy is ruined...