Serious question: what would make prediction markets investable for you?

I’ve been following prediction markets for a while, but it seems like they haven’t really crossed into the mainstream of investing.

Serious question: what would make them investable for you? Is it a matter of regulation, liquidity, trust in resolution, integration with brokerages, or something else?

I’d like to hear what would actually move the needle for investors who think about risk/reward in a structured way.