I will paraphrase the statements of several wise men (since I'm not sure if I can remember the exact quotations):
1. You will probably never neeed a gun. But if you do, you will need it more than you have ever needed anything in your life.
And my personal favorite, short and sweet...
2. Carry 24/7, or guess right.
I think that the OP's question contains some excellent analysis.
There are downsides to carrying. You can't, for example, have an accidental discharge if you don't carry a firearm.
Sorry, but this indicates very limited reasoning. Taking this form of logic to its inevitable conclusion:
--If you never set foot in a car, you will never be in an auto accident.
--If you never take a bath/shower, you reduce your chances of slip/fall accident to near zero.
--If you never walk out your front door, you will not be struck by lightning.
--If you live in a cave without electricity or gas, your chances of a home fire drop to near zero.
And so forth, and so on.
Additionally, most "accidental discharges" are actually negligent
discharges. Both are exceedingly rare, and you can reduce the chances of both to near zero by a) carrying a modern weapon in good condition and b) adhering to the Four Rules.
Bottom line: You cannot eliminate risk from life. You can evaluate and mitigate risk, and most people do so many times per day, without conscious thought.
There are things I can control, and things I cannot. Not carrying is abdicating control of one of the things I can
control, and hoping that the best in human nature prevails.
The older I get, the less faith I have in human nature. And at 55, I sure can't run like I could at 25.