If someone ends their stream early, the prediction points should just be returned to everyone.
If someone says they're streaming until a certain time and then end an hour or two early, you lose all of the points you'd bet with if you're on the wrong side of the prediction. This is unfair because there was supposed to be so much more time in the stream for that prediction to potentially come true.
This could happen in terms of a power outage for the streamer or needing to leave early, but the end result is an unfair result.
For example: "This streamer is playing a horror video game. Will this streamer scream 18 times or less OR 19 times or more?" The allotted time in the stream is another 3 hours. The streamer decides to end the stream after 2 hours. Everyone who voted for 19 times or more loses their points because they had voted thinking they had another hour left for the results.
My suggestion is if the stream ends early for whatever reason, no one wins or loses - everyone just gets their points back.