You have to create a larger disparity of force

A motivated attacker isn’t going to be deterred by anything less than using more force against him than he is willing to experience. Rape whistles, yelling the word “no”, or racking a pump shotgun WILL NOT deter a motivated attacker. For that job, ruthless violence is the only solution.

Greg Ellifritz

Emphasis added.

Force disparity matters. And really, when it comes time for you to defend your life, you want the long-end of the stick. As Greg discusses, it’s what works.