To be fair to traditional futures, they don't technically depend on the occurrence or non-occurrence of a specific event. They're an agreement to buy X asset at Y price on Z future date. You may lose money by being forced to buy oil at an above-market rate, but your contract doesn't say anything about the market rate at date Z (as far as I'm aware).

Whereas prediction markets (and some other stock market/commodity option contracts) are explicitly tied to an event. They're saying "I'll give you $1 if this clearly defined event occurs."