If you do not have a website or its simply outdated/complicated, it will turn away thousands of potential sales or visitors to your business.
By having a website that is strategically designed which delivers a clear message will ATTRACT those people.
Your website is open for business 24/7 which means while you are sleeping, potential customers/clients are able to consume your content at any hour of the day. Having a well designed responsive website will work FOR you when you're unavailable.
In today's day and age, everyone is on their smartphones. Not having a website that is mobile friendly can cost you thousands of potential sales.