>>714990676
>how where the sith a threat at all with all the literal backstabbing they did to eachother?

I'm under the general impression (not that I've consumed much Star Wars media) that the Sith are purposefully reactionary and inherently self-culling or self-eliminating.
This post sounds the most correct: >>714990962 Sith exist just to kill other Jedi, Jedi need to die because if they're allowed to prosper they'll subvert the government, steal kids, establish a theocracy, and create imbalance in the galaxy. Sith cull Jedi and then when the Jedi are (mostly) gone they begin to hack down their own kind out of paranoia, boredome, infighting, etc.. And then the Jedi replenish themselves.

It's balance. The whole thing is a natural cycle of two 'extremes' keeping one another in check.