The "thinning of the herd" happens regardless. Child-mothers birthe fatherless babies in poverty-stricken neighborhoods of ignorant welfare dependents, and a huge proportion of the boys don't survive adolescence. Vegans birthe underweight babies with allergies who, when they make it to child-bearing age, are too physically messed up to survive having children. Women too smart by half abort their unborn. Teenaged sons of single moms commit suicide in numbers far greater than teen boys with dads at home. It's all the thinning of the herd.
Packing a gun for self-defense or the defense of those around you, even nutjobs who jump into zoo enclosures to pet the pretty polar bear, is a whole 'nother ballgame.