I own 3 automatics, and they're both a responsibility and a comfort.
In order to be a responsible pistol owner, you must practice occasionally at the range and secure them from any possible irresponsible user when you are not around them (kids, burglars).
In the event that you use one for home protection, remember that you are responsible for every bullet discharged: if you miss, or if the bullet whizzes through an assailant and keeps going, it can go through a wall or window and hit someone next door, or outside, or across the street. Hollow points will cut down the likelihood of stray shots continuing through assailants or drywall, but a stray hollowpoint will do more damage to an innocent bystander.
The decision to escalate to shooting can be difficult. Even if someone has broken into your home, you are on firmer legal ground if they are exhibiting capacity or intent to harm, which can be hard to pin down in the dark and under the influence of adrenalin. Even if you are certain to be acquitted or not charged, the ordeal of an investigation is pretty draining.
Outside your home with a CCW permit, the responsibility is greater, and the number of potential innocent victims higher. Brandishing your weapon to stop an assailant is possibly a terrible idea, because you have raised the stakes to gunfire without shooting, and a crazy assailant may take that as a cue to draw a weapon you didn't previously see. You are often better off only drawing the weapon if you intend to shoot immediately.
And, once you start shooting, you should keep doing so. A gun, contrary to 60 years of television and 100 years of movies, is not a death ray. An adult male can take several rounds and keep going for seconds to minutes.
Once the cops arrive, you will need to make sure you are not holding the gun unless absolutely necessary, and know how to deal with their questions.
All of this beats being killed, or seeing an innocent person being killed, but a pistol is a responsibility.
I am getting a CCW permit next month, mostly for the course; I think it's a questionable decision to carry in places where something bad might happen - better to avoid such places. I also plan to take an additional course on top of that. I have read a book on handling situations where a gunfight could arise (Ayoub, I think, but I can't remember), and it convinced me that carrying is not a simple choice.