Has anyone had success monetizing their community?

My personal opinion is that the main job of a Community platform is to get out of the way of the people using it. So the problem you have with implementing ads, affiliate links and sponsored content is that those things demand attention. They have to distract your members from whatever it is they came to be involved with, otherwise they're not doing their job.

You also, by law if you're anywhere in the EU, have to declare that sort of thing - and your community members are going to feel used as a result. 

I can see paid groups working but you would have to:

a) Provide a group/community experience that no one can get anywhere else for free

b) Provide something that can't be stolen/replicated for free later

c) Get confirmation from your customers that they would pay for it, and that you can provide the level of quality that they would need for the price.

I don't know what your company does or sells, and that's important context that might change the above. 

One area you might want to explore though is acquisition via community. You can see InSided doing this right now with their referral program, and there's lots of examples elsewhere of community driving advocacy and lead generation. It's a very measurable way to do community value, and less intrusive than ads.

Good luck - that's a tough ask to receive.