Parashat Ki Tavo: What's Going On Here?

What's going on here? מַה זֶה?

What if there’s just one pizza store in your town, and you open a second one? What if your pizza is more delicious, and everyone starts coming to your store instead of the one that was there first? Was it ok for you to take away business from the first pizza store?

It’s complicated, but this might be a case of הַסָּגַת גְּבוּל (hasagat gevul, capturing the boundary). This concept first comes up in our parashah.
Moshe tells Benei Yisrael that anyone who moves their neighbor’s boundary line should be cursed (Devarim 27:17). You can’t move the location of your fence to make your own property bigger by taking over some of your neighbor’s property. This is the basic case of hasagat gevul.
In the Talmud, this is also applied to other situations in life.
For example, if someone has spread their fishing net to catch fish, then another person isn’t allowed to come by and set up their own fishing net right next to the first net. It’s considered unfair for the second person to catch fish that would have otherwise gone into the first net (Bava Batra 21b).
So, what do you think about the case of the pizza store? Is it hasagat gevul - just as unfair as the case of the fishing nets? Or should it be ok in this case? What’s your argument?