Affiliate marketing makes it easier to scale because you're latching onto other metrics outside your own sphere of influence. Once you've found the product or service you can believe in, it's easy to promote that to people worldwide via the Internet. Furthermore, it leads you to ancillary products and services that might provide additional affiliate opportunities.
If you have a budget and are willing to pay for traffic, you might want to explore investing in Facebook Ads, Google Adwords, Bing Ads or any of the other networks you can buy traffic from. Their first advantage is a double-edged sword. You can literally start receiving traffic within minutes from starting a campaign. But once you stop running the campaign, the “traffic tap” stops.