Where is the Steemit revenue model?

Steemit is growing in popularity and as it is growing old questions get revisited. I've googled around to look for the revenue model of steemit but have not found it other than mining Steem. This of course leads many people to ask, is steemit a ponzi? Well, I'm not sure. Investors aren't really being paid out but the claim is that users don't require investment. So while it is not directly a ponzi, I'm still concerned that the money coming in from investors who buy steam get siphoned out via popular users content publishing. 

Please correct me if I'm wrong but it looks like the source of the funds that content producers make is from investors who buy the STEEM. STEEM is also converted into STEEM Power which transfers the wealth to content producers. Considering the userbase of both readers and producers is small, this is sustainable but over time and as the network grows the issue of liquidity becomes an issue. 

From the white paper:

STEEM and SP holders gain leverage when members of the community are willing to hold SMD. This leverage amplifies the gains from growth while also contributing to growth. STEEM holders do suffer from increased dilution if the price falls. Cryptocurrency projects have shown that the gains from increasing the user base willing to trust the network with capital ultimately add more value to the network than any dilution that may occur during a downturn.

In the event of a liquidity crunch when there are many users and investors move out. This can cause an awkward scenario where dollars are converted out prior to payments being sent out. It appears there is a wait period of 7 days or less depending on your rank but still I question if the network grows and the price drops how can Steemit continue to operate? Ultimately, I see investors are the revenue model feeding the content publishers and curators Steem Power. Based on the white paper, it looks like they are relying on increasing the user base with capital. Of course what they can also do is decrease the payout to be sustainable but still investors are paying out with no other model of revenue coming in. This leads me to wonder, what happens when investors decide they've had enough? The only way to earn a return is by having more investors buy up the newly mined STEEM. It relies on people continuously pumping money in while its drained out by producers and replenished by minting new tokens. 

Also in the white paper: Replacing Advertising with Blockchain-based Content Rewards . This section is also a bit strange to me if they are replacing advertising with rewards. Advertisers are paid and pay to place ads for purchase. So revenue comes from up the chain when people buy goods and a portion of that goes to the advertising budget. With blockchain-based rewards, the content rewards is based on mining and exchanging tokens for dollars, in other words investors pay for it. 

If I am mistaken or there is another way for people to earn revenue, Please let me know below. I'm cautiously optimistic but this is one issue that I can't figure out and maybe someone else has already answered it. I've read portions of the white paper to look specifically for how money enters the system. There seems to be two places. 1.) Mining and selling tokens 2.) the internal market where users buy STEEM to promote their content. However is 2. is successful, then it drains the main fund faster. Anyways, please let me know your thoughts.