Polymarket looks interesting but crypto/blockchain isn't necessary for prediction markets-- with Polymarket you still need a trusted entity to record whether the event happened. There are much more legitimate non-crypto prediction markets -- this new one is actually federally regulated in the US https://kalshi.com/
Some of these prediction contracts can be resolved using a decentralized oracle (I know this is the model Omen was trying to implement).
But even if there is a trusted entity involved, a smart contract I can interact with directly using blockchain transactions is better than having to provide my picture, passport and SSN to some company that builds a database of all my trades. This problem is even worse if I move to a jurisdiction where you need to be accredited to play, or where prediction markets are illegal.
For many of these financial applications, crypto/blockchain isn't strictly necessary, but it can be very useful.
