I'm imagining something probably horrible and fascinating at the same time:
You could almost imagine world events being "democratized" by these markets at this point - a significant event will happen (or not happen) by the grace of who is betting on what outcomes and how much volume is at stake. If you subscribe to the view of human history as being staked to material outcomes, then at some point the PolyMarket betting volume becomes an important variable. Betting volume on an event may subsume the actual material interests.
A terse example: two rival kingdoms exist, and it is generally known that kingdom A wants to annex a sliver of the other's fertile interfluve. General consensus is that this will someday happen. Now introduce PolyMarket, what happens? You have people in both kingdoms (and the rest of the world) betting on when/if it will happen. At some point, maybe the betting skews more towards the annexation never happening, and the volume continues to rise as the scales are more tipped. At some point then kingdom A has to contend with the massive amount of value they will subsequently create or destroy if they choose to pursue annexation. Individual actors within the working bureacracy of kingdom A will inevitably use the privileged information at their power to enrich themselves via the market, further tilting or manipulating things in one direction.
We're sort of already there... there were several reports about massive "wins" in these "markets" on betting on the day the US would strike Iran.
It's not democratized, in the sense that everybody can play. But, the markets are for sure giving people with power/access/money reason to vote (in the markets) and vote (in whatever org they hold power).
It's disgusting.
Unfortunately what you're describing is precisely the opposite of the meaning of 'democratised'. A more accurate term would be commoditised. In this case the capacity to manipulate events becomes as tied to wealth as it is to access to information.