Facebook marketing works. But I think you have to look at it from a different approach. Social media is about building human-to-human relationships. That's why ads don't work too well. But there are companies who do get good conversions with FB ads. Depending on the creative, the product and demographic.

There are 3 things that I've done to make social media work for me.

Actively sharing content - I use a combination of Feedly/Buffer to post content. So it automatically posts 5 times a day. My followers like, re-share, and comment.

Be engaging - If people message me or comment, I always respond. I believe having a high quality one-to-one relationship is important above all else. I NEVER ask them to try out my product on the first conversation. NEVER. Most of the time I get turned off when businesses do that to me.

Audience building - I think this is the hardest and most important part. If you have no audience there's nobody there to read the content you're posting. And in turn there's nobody there buy the products you're selling. You need to actively find people to engage with.