Here's the thing about competition, a well run, well rounded store is shielded from direct competition. You can't generally steal customers. It doesn't work that way. If you could steal customers, game store owners would have endless online debates about their favorite Zippo lighter style rather than preferred brand of point of sale machine. The tool would be fire. Just burn down your competitors store and voila! Instant customer base. Instead, we see this figurative burning down, petty back and forth bickering and low ball giveaway events, between small stores.
This is because a poorly run, narrowly focused store is entirely vulnerable to having customers stolen. Customers will be taken and their store will die. If all they sell is Magic, their tool chest consist of a calendar and price. That's not even a tool belt, more like a pair of hammers in your back pocket.
So the same customer base runs back and forth between stores as each store owner races to the bottom with customer appreciation events for unappreciative customers. Here's a tip, run customer appreciation events after customers have shown loyalty to your store, rather than trying to constantly bribe them. What a clown show.
I know all about this because we experienced the clown show first hand. I had competitors open to steal my customers because of their superior pair of hammers. However, because we were well rounded, and sold many other things, we shrugged and waited for them to implode. When they imploded, the competitive Magic community came back (which were really perhaps half the people who bought Magic). You can't build a game store with a pair of hammers.
If you're looking for a solution to this problem, it's pretty clear. Your construction skills are weak. It's not about pounding with your hammer. A solidly built, diversified game store is built to weather the storm of the ups and downs of the game trade, as games and customers ebb and flow. If the need to succeed at any one game or the need to cater to any one community is enough to sink your store, you are a slave. Your stated goal to run a small business and be independent is a lie. Put down the hammers and start building value for yourself and your customers.