Because absolute majority of men are fucking retarded and are willing to do anything to win woman's favor.
They simp in every way imaginable just to get a crumb of pussy. White knighting is nothing but their attempt at gaining the maiden's attention.
If woman stabs you and you retaliate, a bunch of random retards will attack you on instinct.
Men are even willing to go to wars, just because of the prospect of wet pussy waiting for the heroes return. There's a good reason why the white feather campaign was pushed via women and why that war hero narrative is also female centered.
It fucking works.
In short, men are beyond retarded and the cause for all of this systemic misery towards other men.