When you own a store, you have to pay employees, electric, water, rent and insurance. You don’t have any of those expenses with an E-commerce site.
You have to pay for the site, logistics and possibly warehouse employees. You might also have to pay for the company that ships your goods, but these costs are considerably less than if you had a store.
You can afford to lower your price, which attracts more customers. You still will make a huge profit, but the margins are lower. You would make up in volume what you lose in store sales. And, in stores, you have to mark up your prices so high because of overhead and other factors, such as theft.
You don’t have to worry about theft with an E-commerce site. Online sales allow you to be creative with your specials and discounts too.