Do not get a firearm unless you are willing to use it. Many people go out and get weapons with the thought that they will just waive them like magic wands to make bad people go away. It doesn’t work that way. Most people flinch at the idea of actually killing someone. It is not unusual for soldiers in combat to be unable to fire at a living breathing human being. That’s why a lot of the training soldiers go through is to make obedience a reflex. That’s also why a lot of effort goes in to dehumanizing the “enemy”–it makes it easier to pull the trigger.
So: only pick up a weapon if you are truly willing to use it. This takes a lot of self-knowledge but, if you are sure, then OK.