When you're running an internet marketplace (Etsy, OpenTable, eBay, Uber, KickStarter, Yelp, etc.), it's very tempting to give sellers the opportunity to buy premium placement. This could be things like homepage placement, better placement in search results or enhanced profile pages. Selling this stuff is certainly a very logical way to monetize your user base.
But the problem with this approach is that every time you give priority to a seller that pays you more money, you've muddied your value proposition and taken an equal amount of value away from your user base.
A good marketplace is one that creates an easy, beautiful, seamless and open buying experience that enables rating and recommendation systems so that users can decide the best sellers and the worst sellers. Selling premium placement effectively circumvents your users' preferences putting you in a race to the bottom.
Sure, by charging for premium placement, in the short term, you'll generate some cash. And you can use that cash to do some marketing so that you can generate more users. But over time, if you want to continue to grow, you'll need more and more money and more and more marketing. That will force you to create more and more premium placement options (subsequently devaluing your marketplace).
The better approach is to prioritize the user and compete in the race to the top. Give your users the best possible marketplace experience and let them decide which sellers should win and which sellers should lose. Those great experiences will result in buyers telling their friends to use your service and that will result in more people going through the experience and more people telling their friends to use your service and on and on.
That's the way to scale. And you can't do it favoring one seller over another. Give sellers a great experience too, but don't prioritize them. Prioritize the user.