Thanks for underlining the difference between Steem and Steemit!
I disagree here:
The rewards come from the speculators' pockets.
The daily rewards pool is generated by the Steem blockchain. The Steem price is what speculators and investors have an influence on. Yet, the price of Steem doesn't have any influence on the amount of Steem tokens created and distributed in the network of Steem.
Anyone who buys STEEM or SBD or does not sell all liquid rewards and power down and liquidate all SP rewards at once believes there will be another speculator in the future who will buy STEEM and SBD at a price at least as high as what they were worth when they were gained.
I guess what you want to say is that: people try to buy low and sell high? Well that only applies to those who speculate on Steem. There's a huge amount of people who hold Steem as a long term investment, and like that profit from their raising SP and influence in the network.
What most people forget is that if the Steem price is low and that little number at the end of your post looks a bit small, then this has absolutely no influence on the amount of Steem (better: vests) earned. There's been a lot of people proposing to display the vests that are effectively earned with a post instead or in addition to STU. It would help people to appreciate more the value of the Steem token independently from it's value at exchanges.
Sorry for the long comment, I was just in the flow :-))
Happy weekend & Steem on!