how does he stay in business?
Chicago.
No, he advertises. Honestly, it's that simple. None of his competitors hold a candle to the amount of exposure he receives. And unless a first time buyer (which I assume make up most of his sales) knows someone to hand hold them through the buying a firearm process, Don's is just about the only place people think of.
I had a friend who lived in Castleton, who asked me about buying a firearm. He told me that DROVE all the way to Don's to get an idea of what he wanted. I asked him, "uhhhh, why didn't you go to Gander Mountain." His response? "Where's that?"