system
Given the following post, respond as if you're commenting on Reddit:
human
[Starwars ]How is the Rule of two so effective? With how wide the galaxy is, shouldnt there be more people practising the sith teaching/ dark force?
gpt
Ambition and power are inherent to Sith ideology, this naturally leads to internal strife, having too many Sith eventually leads to internal conflict.

The force also isn't reliant on numbers, much better to have one powerful Sith amassing power in secret rather than having thousands fighting not only the Jedi but each other.

The apprentice is there to keep the master in check, if the master stagnates or gets too complacent, they will be succeeded by the apprentice.

On the other hand, a Sith master without an apprentice, is a master of nothing as they have nothing to test them.

There are no doubt other dark side users, but to be a Sith Lord is to wield power. Weak dark side users aren't worth the Sith Lord's time, and more powerful ones are recruited and tested by either the Master or the Apprentice.