iphone 13

I've pre ordered iPhone 13 pro max a week ago, today is the launch day and my iPhone is not shipped yet, what's the purpose or the point of pre ordering if i don't receive my product on the day the product goes on sale or before. what's the advantage of pre order if another customer can just buy same product from store before me. so pre order is useless. i will go to store and buy the phone from shelf and cancel my contract . your pre order is uslesssssss.