You could just as easily argue: Why should we try to reduce a rise in burglaries? We have laws in place and it still happens. So fuck it, lets give up.
And the laws clearly aren't addressing it, because we have 15-year olds shooting up schools because they are pissed at the world. So what's to stop us as a society that wants to reduce school shootings to consider: Is there a way we can reduce 15-year olds who want to shoot up schools for accessing firearms?
Radical thought here, but perhaps we strive for both. We can both try to keep every lawful gun owner with open access to firearms, but maybe restrict that to the fucking crazies that want to do bad things with them.
No one is saying they have all the answers. In fact, we know we have to compromise as a society, because we can't all get what we want. But I think we can strive towards whatever common ground we can find. So at the base we can explore the idea of letting the good guys have the guns, and keeping the bad guys away from them.
But to throw your hands up in the air and just quit like you do, isn't just cowardly, it's stupid. You would never apply that logic to any other problem. "We have rule against X, but X still happened, so lets give up."