I got my BS in Computer Science legally carrying a Glock in every class. I think it's very likely I was the only person doing so; Not because I was fearful, but because I like being prepared. It takes very little long-term effort for people to carry pepper spray, a gun (if able), and a first aid kit everywhere they go. You never know who's life you might save.
There's been exercises where you simulate active shooters with some or none of the people armed. As I remember it the situation with some of the targets were armed ended up with higher casualty numbers in quite a few simulations. The solution to a bad guy with a gun might be a good guy with a gun, but it also might be easier paths to run away and lowering the probability of a bad guy getting access to a gun.
Looking at the non-US stats, it's pretty clear the latter is at least a lot more credible.
I'm actually not surprised. As a conceal carrier, I think that most people that conceal carry a firearm are woefully under-trained and potentially a liability. I still absolutely encourage people willing to put in the effort to do it, given the potential to save lives. Pretty much every single active shooter situation only ends with the suspect shooting themselves, or being shot - I want every chance to end the threat possible.
Something, something, forest, trees.