I disagree. I think if lots of people have it, it shows support to the people that want to ban or limit it.
Plus if you have 100 million people on a list, how useful is it?
I have one on my car and I'm not taking it off.
Discussion
Most of those who want to ban or limit guns will look at your sticker and just think you're a dickhead, a) for being a gun freak and b) for putting a gun related sticker on your car. I wouldn't put a bitcoin sticker on my car either.
There are downsides to it, but I disagree with your inference.
I think every gun owner should have gun stickers on their car because that will be a net positive