Because we've allowed a large portion of the public to conclude: 'Guns are scary'.
As irrational as it is to think that law abiding, responsible citizens (armed) are somehow a threat...that's where we are folks.
The public doesn't know who we are (just ordinary citizens going about our business each day) because we hide our weapons.
So quite naturally the carrying of a weapon for self defense NEVER gets 'normalized'.
The guy with a ring in his nose, pierced ears and a big, honking tattoo of Satan on his neck..doesn't get a second look these days. We've all seen it a hundred times and the shock factor has long ago worn off. But let Mr./Mrs. average citizen open carry into Walmart anymore and someone is going to pee their pants. Sheeesh....!
When the gun toting public isn't willing to stand up and fight for what they believe in, call out the nonsense, then we get exactly what we deserve.