There can be so many considerations for what gun you carry;
Size of the gun, weight, capacity, caliber, state laws, type of clothes you're wearing, where you're going, activity level, where you live, comfort level, eye sight, fitness, injuries, body type, etc.
What someone else carries can be an influence but it's way down there on the list of all the other considerations.
Here's another angle...how many of the top level instructors have been in gunfights as civilians? (Not counting their past LE/MIL duty).
The point I'm making is that the industry professionals promoting carrying guns are making their living off of classes that revolve around carrying a gun.
Yes there's a significant business angle to the gun culture and it's wise to at least keep that in perspective.