There has been a lot of mayhem since last night and I'm not going to try and address all of it so here's a few observations.
Self-defense is layered, like an onion or a parfait or an ogre. The absolute first best thing to have is the mindset. If you're wandering around in Condition White (to use Col Cooper nomenclature) and blissfully unaware of your surroundings you will not only be less likely to defend yourself effectively but will actually draw attention for being an easier mark in the first place. For instance a female walking through a parking garage head down watching a tik-tok video is basically going to be perceived as a prey animal.
Any halfway decent instruction in physical defense is a good thing. Whatever particular discipline one may consider superior even the "lesser" ones are better than none at all. Now having said that even high level hand to hand training has limitations. If facing an individual of roughly the same physical ability it's a decided advantage. If facing a physical superior it can at least level the field a bit and often catches people off guard. If facing someone with weapons or multiple assailants you're in trouble, particularly if the opposition also has any idea what they're doing. (Why do so many people assume the "other guy" will be a clueless pansy?) I always find it amusing when people with a certain bias come up with essentially some variant of "I'll just whip dey ass!". It's naive as hell.
Introducing weapons into the mix gets complicated quickly. Common are things like knives, pepper spray, stun guns, various impact weapons and firearms. All can be useful at various times for various usage. (An obvious one being some places prohibit carrying of some of them) As alluded to above with martial arts training a "weapon" is not some magic talisman that wards off evil. They are inanimate tools that can expand one's effective use of force in a defense scenario. Likelihood of success is greatly increased with familiarity and proficiency. Firearms get the most notice because, quite simply, a personal firearm is the most efficacious option available to project force or the threat of force. It is in fact a force multiplier that can make even the tiniest of cheerleader flyers into someone capable of putting down or send scurrying multiple would be assailants that would otherwise be able to subdue even a large and trained but unarmed man. Better still while the more trained the better the learning curve is a hell of a lot less than other disciplines to become functionally proficient AND the deterrence factor is much, much greater. Far more often than not having a firearm brought into play makes pressing anything less than the most determined attack not worth the risk.
The loss of nuance is one of the dumbest (and most common) aspects of these types of discussions. Someone carrying the best of handguns should also be of a situationally aware mindset, have at least a rudimentary understanding of hand fighting (even if only to create space and allow for firearm access) and be learned in the use of that firearm. Anyone that just says "I know karate!" (or whatever) and thinks it's all good is just as delusional about their safety as someone that says "I've got a knife/collapsible baton/gun/whatever!" and thinks it's all good. The real world is too unpredictable to think that way. You absolutely are not "safe". You can be more safe by manipulating what is under your control to your advantage. That's as good as you're going to get.
As an aside the funniest thing brought up in any of these things is when somebody declares any variation of "I've never felt the need for X." I wonder how many people have ever been assaulted/carjacked/raped/murdered/whatever and left their home that morning expecting that to be the case? The world doesn't give a tinker's damn about how you "feel". This doesn't have to be self-defense related. Not checked the pressure on your spare lately? Sucks you didn't "feel" like you might really have a flat. Not had your fire extinguisher charge checked? Sucks if you didn't "feel" that to be anything to really worry about. (we could do this all day) In the end self-defense is exactly as it reads...defense of self. How much or little one cares to put into it is up to the practitioner. The only truly bad people in the mix are those that deign themselves worthy of limiting the ability of others to do so.