From what I understand of the situation you've described, the Predictor doesn't seem to factor you opening Box B into account at all. In addition to that, you've not mentioned the Predictor's accuracy rate.
As such, it seems that the Predictor is relying on you checking Box B and finding it empty - because if you do, then you're definitely going to take the thousand euros and leave. If he put a million euros in Box B, then there's nothing to stop you taking both, and his prediction would be wrong.
Naughty bad hypothetical!
As such, it seems that the Predictor is relying on you checking Box B and finding it empty - because if you do, then you're definitely going to take the thousand euros and leave. If he put a million euros in Box B, then there's nothing to stop you taking both, and his prediction would be wrong.
I think the Predictor is a bit of a prick!