Until we do. You see, the ironic thing is, the more you push back on sensible gun laws that would keep stuff like this from happening, the more you get people against guns in general.
Gun owners are only 20% of the population. The majority makes rules the rest of us don't like all the time... that's called civilization. Maybe you've heard of it.
The rot is teaching people that their problems could be resolved with guns. Salvador Ramos without guns is just an angry kid who was going to have to learn how to deal. Salvador Ramos with guns is someone who was going down and taking a lot of kids with him.