When you gain page rank, you'll be able to make money with your blog by accepting paid posts, ads and more. And when you gain ranking on search engines, people who are interested about your topic would be able to find you through these search engines.
Just like here in Bloggers Tech, possibly you found this blog through the search engines, social media, or from your friends. Your audience could find you at these search engines too and start building your name and your blog's reputation online!
Building backlinks to your websites is a crucial part of SEO for just two reasons: