Horray! Simple riddle finally solved.
-I have destroyed worlds (Taris and Dantoonie)
-but I have never felt any peace (Malak is under the shadow of Revan and wants to live up to it).
-I have destroyed a foe of mine (Malak destroyed Revan)
-but never felt any sastification (Malak wants to prove that he really is more powerfu than Revan)
-I have many followers, (Leader of the Sith Empire)
-but no friends. (The Sith respects the powerful, and always want to undermine each other. Even Bastila said that after she kills off Revan, she would then kill off Malak and take over the Sith Empire for herself. Nobody really loved Malak.)