Just because someone likes your page doesn't mean they get to see all the posts you make to it. In fact it's like 18% or UNDER that actually see any of your posts on a fan page. So you get a ton of likes and then what?
That's the second part. All these courses never show HOW to make money from the likes. They just say "get them". People, there is a reason you can get likes for $0.01 to $0.02 per like. Want to know why? Likes are crap. FB knows this and they're milking this "like" train to no end.
If you really don't believe me and want to get likes for cheap, go ahead. But at least monetize them somehow. People on FB do buy things, but it's a different beast versus the typical paid traffic sources. Use it wisely.