After people like your page good things happen. Facebook starts showing to them your new posts, which brings more likes and shares, and possibly creating viral loop snowball. More people seeing posts also means more people commenting and clicking, which in turn allows you to build a list and make profits.
While you can invite people who liked posts manually, one by one, it could be extremely time consuming to do every day. Socicake Inviter extension adds “Invite All” button to Facebook page in your browser. All you need to do is to click that button and let software do the work.