Dynamically priced posts. Words (or better, topics) are priced based on their relative demand, and you pay to post. You earn some % of the total paid for the topic based on the engagement your post gets. If you're the first person to post about Powell's speech then you get it for cheap. After 100's of people have posted the same thing, it becomes too expensive for anyone else to pile on with the same, low quality, or repetitive takes. You need to be sure you're adding something interesting to put the money up.