We can safely say that nowadays in the "Google era", SEO services are a commodity. If people link back to your content, it means it's valuable. And not only do you get direct views from those backlinks, you'll also look good in the eyes of Google.
So you need content, keywords, backlinks & more to get #1 rankings. We all know the drill. Except, getting everything done is time-consuming, so more and more people are looking to outsource everything.
Bottom line is:
There's a huge market for people who want SEO services. In fact, we did the math and ended up with a market of 320,000+ customers.