TheBoost said:
If I'm an evil Sith Lord, motivated by Greed, Hatred, Selfishness, and all that, and I'm awesome and really dig being a Sith Lord... why do I train an apprentice and instruct them to SOMEDAY KILL ME.

People will do a lot of strange things in the name of religion. In that sense, the sith are not entirely selfish, since their selfishness is actually a means to the survival of their order. Of course with Sidious it kind of ended up all blowing up in their faces, because he was constantly plotting to find more powerful apprentices to replace his current one. In that sense, he was the most selfish of all Sith since he'd plot the demise of his own apprentices instead of the other way around.