I grew up with handguns, rifles, shotguns, etc. on a farm in southern Indiana and (while rusty) I would consider myself of at least average capability.
Still, I have no illusions of the testosterone fueled fantasy of super-capability, fending off the imagined armed invader.
The most likely injuries that are outcomes of owning a gun, statistically, are, in order of decreasing probability:
1) an accidental shooting by a friend or family member of a non-criminal
2) an intentional shooting by a friend or family member of a non-criminal
3) an accidental shooting by the owner of a non-criminal
4) an intentional shooting by the owner of some non-criminal
5) theft of the gun by a criminal, who shoots the owner or a family member
6) an intentional shooting by the owner or family member of some criminal, their Rambo moment and chance to get on Fox News.
Good gun education, training, gun security awareness, and attention to routine secure storage can lessen, but not eliminate, issues 1-3 and 5. Basic sanity can lessen but not eliminate issue 4.
Issue 6 is still, however, the unicorn scenario, for most people. If you live in Alaska and the sheriff is 100 miles away, sure. But it doesn't make sense for most people.
A better investment is monitored security systems, many cameras, automatic alerts, etc.