They can calm down and maybe have a better day that will stop them from killing themselves. Some argue that background checks are a problem due to one day only gun shows. This comes down to a simple weighing of consequences. State offender Bob could go to the gun-show and purchase a gun now. He could shoot someone the next day.
Guns are a part of the world.
We can t take that back. They have helped us fight the bad guys. But when in the hands of criminals or potential criminals, the guns become instruments of evil. Waiting periods and safety locks are a logical step to prevent unnecessary violence. Gun control saves lives.