In general I don't believe idiots and scammers need any special help getting relieved of their coins sooner or later.

Wagers separate conviction from performance. Opinions are cheap — positions cost something. When capital is at risk, the incentive structure shifts from tribal signaling to actual accuracy. Every contentious Bitcoin proposal could be priced in real-time with fork futures. Do you think prediction markets would change the tone of protocol debates or just concentrate them among the wealthy?