Why not? There's nothing at Walmart that you can't get somewhere else. The appeal to shoppers is that they generally have the lowest prices, but that's it. If your only goal is to save a few pennies then shop there, but if you're fed up with their BS then there are most certainly other options.
There are 2 or 3 things from Sam's that I literally can't get from somebody else. It's their store brand stuff I like.
And... I go through about 100 cans of brake clean a year from Walmart, buying from somewhere else is literally double the money, so about an extra $200. I'd get more mileage giving that $200 to GOA than I would Autozone.
That says nothing of the people who really don't have other shopping options in their immediate area. If I really wanted to, I confess I could just dump Wally and never look back. It would cost me money, I wouldn't have things I want, and it would be less convenient. But, there are some people that can't afford to do that. When Wally is the only real store in your county, what are you really going to do?
So... I admit that I'm not being as strong of a 2A guy as I could, I've confessed what I'm already doing (reduce my support by about 80%), and stated what I'd be willing to do in the future (participate in widespread, LARGE, organized, boycotts). I can pull the wagon for about 80%, if it has to be all or none or I'm just as good as a gun banner, then I guess we're just not going to be friends (and I'd honestly like to be friends with everyone here, so, not ideal).