There is a difference between value creation and value capture. It's a massive difference. While we can all agree that things of value are being created on Steem every day, the problem of value capture remains. There are plenty of examples of value creation that do not capture value. The stay-at-home mother and all the work she puts in caring for her children who become productive citizens creates a lot of value but captures little to none because nobody pays for it.
The STEEM token has basically four ways of value capture:
A) Tipping
It is possible to buy STEEM or SBD and send them to authors whose work we appreciate. Steem has a common reward pool, the ownership of which is divided according to Steem Power owned. The reward pool is jointly owned by all the stakeholders. When a stakeholder upvotes someone else's post, they are sacrificing an opportunity to upvote their own content and sending the author rewards to someone else. In that sense, upvoting is exactly like tipping.
It is conceivable that someone purchase Steem Power for the purpose of being able to reward others from that portion of the inflation pool the Steem Power held by them entitles them to control.
B) Advertising
Value is in the eye of the beholder. The value of Steem posts will have to be extracted from the beholder because that's where their value is. When a beholder does not want to purchase Steem Power to reward others or wishes to use it to do something else, the creator can do little else but to sell a merchant space for an advertisement next to his creation so as to get the beholder to divert some of his attention to that.
C) Speculation
Speculation is a time-honored way for various vehicles to capture value. As the native cryptocurrency of the Steem blockchain and listed on several cryptocurrency exchanges, STEEM is well-positioned to capture value that way. A very large portion of even STEEM's current bottom-of-the-bear-market value is speculative. Speculation is at best a zero-sum game, although in practice it is a negative sum game owing to the overhead costs of the speculative came itself. On Steem, the current 8.5% annual inflation, which is even higher if the virtual supply generated by SBD is taken into account, functions as a tax on the speculators. The upside is so large, however, that speculators seem to accept it. They can delegate their powered up STEEM to various projects to earn passively or if they enjoy content, they can curate themselves.
D) Ideology
Yet another reason to buy STEEM is to support the chain out of ideological reasons. Some may want to spend their hard earned money to flip the finger at the existing financial system and centralized mainstream content delivery platforms that use it.