What makes you think that? A few bard's tales about the pure, human heart winning out over power and envy?
Surely if that was the case, there would be far fewer dragons no? And less evil sorcerers, barbarian kings, and corrupt bastard princes besides?
No; Of course it happens, but the vast majority of those that come to settle the score with pops find they cannot win against their master with the life and power he gave them... and how few still thereafter succeed without furthering the legacy of their ancestor.
You don't think a being that lives in terms of ages would be toppled so easily by an half-potent bastard do you?