Massacres happened on both sides, but one side (the instigators) had leadership telling them to flee, maybe because it wasn't really their homeland to begin with; they were just settlers from all over the region. And the other side stayed, because it was their ancestral homeland.

Have you done a survey, like how many people ran away because of the massacres per se, and how many ran away because their leaders told them to (for reasons unrelated to avoiding a possible massacre)?

You seem to assume that it is 0% of the former and 100% of the latter, which I find dubious.

Because even if it is let's say 50% and 50%, it is no longer true to say that all have left voluntarily.