People who carry a 5-round snubbie are probably laughing at this thread.
Remember, a police officer has to remain on the scene in some respect. Might have to pursue a fleeing suspect. You don't.
In almost any case imaginable, if you produce a firearm and start using it, it is unlikely that the assailant will wade into your gunfire, taking hit after hit, hoping you'll run out of bullets so that he's only shot 7 times.
If you cannot drop a target with 7 rounds of Corbon DPX or similar, I doubt 14 are going to be much more help. And per the above, what is the scenario you envision? You, hunkered down behind a dumpster, a hail of Bad Guy gunfire smacking all around you, as you desperately reload and pop-up gopher style to return fire?
What we see in real-life videos in virtually all cases is the defender fires a shot and everybody scrambles to get the Hell out of Dodge.
There are exceptions: The maniac, the drug addict, the disgruntled ex-lover. Sure, it happens. But there you're getting down into statistical territory that's very small. In general, the odds of a CCW owner having to actually produce and fire a weapon are low.
Nevertheless, I'm glad I've got options beyond 7 rounds, because ya never know.