Getting the most value from your marketing campaign means making it accessible to as many people as possible. If you want the most sales, sign ups, or entries, you have to spread your message.
A quick disclaimer: While it’s possible for a campaign to go viral, don’t depend on it. There are just too many variables at play to make something go viral, and many of them are out of your control. If you have to reach a million people to make any money, you should rethink your strategy.