When talking about earning without spending capital (money), frankly I say that to get free money on this forum by promoting a project or joining an Airdrop. I also say there is no guarantee after promoting a project can generate (money) for you. as I know that there are many types of fraudulent projects although not all projects end like that.
Too bad you only say quantitative value about this forum. Why should you rely on income? actually when quality can explain everything and there is no need to state everything by participating with campaigns etc which makes it as if this forum has no other interest. See that in fact it will follow when we have quality, if relying solely on revenue means you are not empowering the purpose of the forum for much more useful discussion. There's nothing wrong with that, but there's a lot more valuable knowledge on this forum that you can't discuss out there.
As a suggestion, take a look at their project which seems good for you research.
https://bitcointalk.org/index.php?topic=5364555.msg58171048#msg58171048