Very few prediction markets that could exist actually do.
Not because of a lack of interest, interesting events happen all the time, but because the infrastructure to support niche markets doesn't exist.
If a market maker can't price the likelihood of an event happening, there will be no liquidity for users to trade against, no matter how great the demand is to speculate on that event.
Permissionless prediction markets are inevitable because the breadth of topics that people would speculate on but can't yet is massive. The last blocker is making markets that are liquid enough to support traders no matter how niche the topic.
The PMM solves this.
Very soon, market creators will be able to launch markets and only consider what is important to their audience, not what is likely to be liquid.
The most popular markets will no longer be those that can be priced by a market maker, and finally reflect what people are most interested in.