Many places the NRA is fiercely hated, at the minimum you may get your paint scratched.
There's many reasons not to do it.
I used to have NRA stickers, but I took them off two or three years ago. But not as a concern for thieves. Mainly for those that have opposing political views.
I have a family member that works at a large hospital, and dares not to have anything gun related on the car or Facebook.... And has to hide political affiliation, or pretend to hold another.
It's not just about crime, sometimes just to keep your job, or avoid unwanted attention.