How do you think similar businesses stay in businesses? (i.e. Krogers, Walmart, Giant Eagle, etc.)

I’ve been asking questions about business lately and you guys probably know why. But anyways, I was just thinking…how do you think businesses like Walmart, Meijers, Kroger, Giant Eagle, etc. stay in business when there are so many other big named groceries out there? What do they do to stay in competition and not lose from the other company…especially when they started up and there’s the “big” guy? Krogers is especially similar to Giant Eagle as is Meijers. I know how Walmart is different since it has “everything”.

Just curious! Same goes for my parents store. I was thinking we were one of the first groceries to open up along with some other Asian store 30 minutes away. Now there are so many! I always ask my dad how we stay in business and he just says customer relationship and our variety of things from different ethnic groups (not just Asian).