Well, that's just what I believe.. I don't think every Sith there is has turned on his/her master. Yes, it does happen occasionally, especially since it's a part of the tradition, if you are to believe what they say at the Sith Academy. But it had depends on a number of things.
Besides, your character won't be a Sith (or at least not until you get a prestige class). A dark sider, yes, but not a Sith, so technically you wouldn't be bound by Sith Tradition . Besides, examples of where the Master just subdues an apparentice who tries to replace him/her has been seen before...
If they are DS aswell then once they feel that they have become better than u they are wont want to follow u. They will want to lead! So they will try to get rid of you!
I dont think its done because of tradition. Its done because they are power hungry, so it become tradition. But tradition or not it would still happen.