Like other people who are selling in digital goods they are earn by selling like coupons aws account i heard that they can earn more of that..
Selling digital goods can be more than or less than 0.1 depends on the outcome of the item you sell if it is indemand or not.
There's not that much skills needed in managing a campaign so I wouldn't really say "Very good in this field" to someone that's managing a campaign for quite a while. This forum is mostly about trust. If you have negative trust, no one's going to have a deal with you no matter how good your offer might be. Take a look at new campaign managers, they can hardly get a campaign to manage. But since Yahoo has been around for a while, people are taking his service instead.
Managing campaign can totally be programmed with very little human intervention. You can create a script that checks the length of the participant's post minus the quoted part and then at the pay day, a human will check if the posts actually made any sense and is not just lengthy. This is what the Bitmixer campaign does. I bet that in the future most campaigns will be like this. It's more practical since you just have to pay one time for the script and then pay little to the manager since he only have to check if the posts made any sense (and I really think that eventually even a bot will be able to do that).
In other words, getting a job here like managing signature campaign doesn't necessarily mean that you're excellent at it or you're the best at it. Most of the time it's just about the trust.