This might sound odd coming from a guy that runs an agency focused on search engine optimization and Google rankings, but anytime we launch a new venture within the agency, I aim to launch the business solely on the back of online advertising. In short, we pursue niches where we can buy traffic from search engines, convert leads or revenue, and make a reasonable profit at the same time - "free traffic" from Google rankings will come, but it will come later.
3 Reasons We Focus on Online Advertising
The short answer is because I'm impatient. Building up a large amount of traffic from SEO for a brand new online business can take 3-6 months or more, and that assumes that you're cranking and doing things right.