Every NRA/Trumpublican argument in favor of guns is bullshit. The one that sounds half-plausible is the claim that guns get used defensively far more often than they are used in crimes, but that turns out to be based on surveys with no real controls for accuracy (e.g., no follow up on, "Yes, I used my gun defensively!" responses to see if they were actually in the time frame specified or if they can reasonably be counted as defensive gun uses).
If you actually want to KNOW the relative significance of defensive gun use (the NRA/Trumpublicans don't), you would conduct surveys very much like those done by Hemenway, Azrael, and Miller
In these surveys -- conducted in 1996 and 1999 -- they randomly contacted 1905 and 2521 adults and asked them if they had used a gun defensively in the past five years and if they had been threatened with a gun in the last fiver years. Affirmative responses were followed up to collect details about the claims, and claims that were deemed illegitimate were excluded.
The results in both surveys indicated that Americans are three times more likely to be victims of gun crimes than to have used a gun defensively.
It has now been 15 1/2 hours since a mass shooting in America was reported.