Everything in business comes down to transactions, so to beat the competition, all you have to do is offer a more valuable or appealing transaction than your competitors. If you’re selling a comparable product, which most retailers are whether or not you want to admit it, oftentimes a consumer’s decision will come down to price.
If you can slash your prices to be lower than those of your competitors, most of your problems will be solved. But, you can’t slash your prices infinitely. You still need to make a profit.