While your website will be accessible to all these billions of people,
25 years ago, very few businesses had a presence on the internet. Almost all of them had a Yellow Page listing. Now many if not all your competitors have websites. Your business without a website is like not having a yellow page listing in 2000. If you aren't online you're not placing your business in front of all those people searching for you. When your current and potential customers are searching for you, at least meet them half way and be there to be found.