If you have a brick-and-mortar shop, you have a limited number of people who can come through your store. Even if you are open 24 hours, you can’t reach as many people as you can with an E-commerce site.
Also, you have global customers, but with a physical store, you only have access to customers in the local area.
If you are sales expert you know that customers want to be able to buy whatever they want with a click of the button. With an online store they don’t have to worry about whether the store is open.
They don’t have to worry if they are wearing clothes or their pajamas. They can have their purchases sent directly to their doorstep.