You're missing the point I'm trying to make. I never said that it would stop criminals from from breaking the law or 100% stop gun related violence/crimes. I clearly stated that if someone wants to break the law, they will break the law. But that doesn't mean there shouldn't be stricter laws in place or more regulations, etc.
The solution and mind-set of "stricter laws aren't going to stop criminals from breaking laws and killing people" is the wrong approach to take, imo. These mass shootings are not just being committed by career criminals, or gang members, etc. They are also being committed by people with mental health issues, etc. with a common trend of these tragedies being committed by teens/young adults with easy access to firearms they should not have.
There are kids who are outcasts and bullied/picked on, who have severe mental issues and once they turn 18, nothing really in place to prevent them from heading down to the local gun shop and within 15 mins or less, walking out with a semi-automatic assault rifle, multiple clips and ammo. Sure, stricter laws/regulations/etc. is not going to 100% stop all gun related deaths/mass shootings/etc.
But depending on how strict the regulations/laws are, it might prevent a lot of those tragic events from happening. Raise the age to purchase all firearms to 21 and require a purchase permit for all firearms (not just handguns), then maybe that 18 year old senior that was constantly getting bullied, made fun of online in every social media platform available, laughed at at school, shunned by their fellow classmates and had no friends wouldn't have an easy of a path to purchasing a semi-automatic assault rifle, 4 or 5 30/40 round clips and taking multiple peoples lives.
Maybe, because they don't have easy access and can't purchase firearms at that age, they graduate high school, go to college, get a job, whatever, and end up making friends, etc. between age 18-21. Maybe then, because it's been 3 or 4 years since going through hell, they got help they needed or just quit hating and wanting to hurt/kill people that were bullying them. Maybe during that time after finding/making friends they realized that they weren't a failure/etc. and their life did have meaning and purpose.
Making stricter punishments for gun owners that do not properly secure their firearms, where their kids can gain access to their guns and use them in mass shootings, etc. Maybe knowing you could be going to prison for a really long time should your child or someone else having easy access (guns not locked up, proof that you didn't do everything to properly secure them) to the guns and using them in a crime or murder, would make them start properly securing them. And then maybe because a troubled youth can't get his dads semi-auto and can't buy a gun until they are 21 (if the age were raised), maybe that prevents another tragedy from happening.
It's never going to be 100% prevented, but damn it, I refuse to believe that doing something (common sense gun laws - just raising the age to purchase to 21 and stricter penalties for gun owners that don't secure properly) will not reduce these horrific tragedies from happening. And at the end of the day, isn't saving as many lives as you can worth it?