Without wanting to sound like a know-it-all, I think the underlying theme between all of them is not really understanding the value proposition for the customer

Without wanting to sound like a know-it-all, I think the underlying theme between all of them is not really understanding the value proposition for the customer. You think it's weird that a vacation house owner wouldn't switch to a free service - I would think it weird if they did. They're probably making twice as much money as they used to, and consider it good value for money. They probably aren't terribly motivated to save a few bucks when the existing site is working for them, and has high traffic. You constructed an elaborate payments scheme for rungjump, but in fact people rarely respond to this type of cash incentive, and introducing payments 'dirties' the whole process. People would probably prefer just to post for the kudos or ego boost. There is probably a lot more money in this model for targeting recruiting ads; if someone is looking at job x and how to get it, recruiters/trainers/educators are going to pay to put an ad in front of them, and you're going to get good clickthrough.