A website is not some magical entity that you simply get and then it just magically generates you business or sales. It is exactly the same as opening a new branch of your business.
There is a setup cost and a maintenance cost, this will get your website up and running, the same as renting office space and setting up your new branch, just much cheaper!
Once you have your website live, you then have to get to advertising it and generating leads to it. Just as you would employ sales reps to generate sales in an office, you will need to have an advertising budget for your website. Your advertising will consist of activities such as Facebook and Google advertising as well as other advertising options relevant to your industry.
If you do not advertise your website, it is the same as opening a new showroom hidden out in the wilderness, you may get a sale or two from adventurous wonderers, but not enough to make your website (your online business), worthwhile.
You can have a lot of automation setup in your website, but there are some tasks that you will have to manually do, such as adding products, writing articles, and advertising it.
If you do not keep your website up to date that would be the same as never maintaining or restocking your office / sales floor, it quickly becomes rather useless to visitors.
If you have a professional website, setup correctly, it will be your hardest working sales rep and your most organized assistant. It can generate sales 24 hours a day, it will never take leave or not show up, it can manage invoicing and inventory, as well as reminding customers to make payments. It can keep in touch with previous customers and encourage additional sales, all with very little input from you. If setup correctly.
Websites can be hugely beneficial and a profitable addition to a business, both big and small, but if they are not utilized properly, managed and maintained, it is the same as purchasing an amazing range of products and then hiding them away in a store room where nobody can see them.