I don't carry a reload because I'm worried about running out of bullets in a gunfight.
I'm not a high priority target, and there's no hit squads out after me.
If I need to defend myself, it will be because some knuckle Head, or junkie, or carjacker, or mugger decided to take a chance on me.
That's not going to be a reason to fire a half box of bullets. Just a few should be enough to make the nonsense stop.
No, I don't need to carry reloads for that.
BUT...
If I use the weapon, It's not going to be full of bullets any more. What about the rest of the day? A pistol with two rounds left in it doesn't sound like a good idea, does it?
I keep spare mags strategically located. (I carry a 1911)
There's a couple in the truck, at my job, on my dresser at home.
If I'm going to be out and exposed, or away from my truck, I have a single mag Kydex off side mag holster that works very nice, and sometimes I'll stick an extra in a back pocket.
But seriously, the pistol alone weighs three pound and extra mags get heavy quick. I don't always carry one.
At some point, it becomes stupid. I'm satisfied knowing that I can whip out a full size fighting pistol if I need to. If That's not enough things have gone seriously wrong and I'm probably not going to make it home anyway.