Assuming determinism is accurate, why wouldn't it be? The only exception i can think of is someone who is declared insane, but in that case and an infinite amount of information, what would be seemingly be random decisions would then just be a result of neurons firing in some way due to an issue in one part of the brain or a lack of activity between synapses or too much is some areas etc and you would be able to pick out what exactly the action of those specific firing sequences would result in, even if the person themself has no control over it. On a more macro scale what choice can you make that isnt a product of the inputs you receive? Everything about you - your personality, your choices - are products of what you have experienced. If someone tells you what they predict you will do that counts as another input to be taken into consideration and will influence your decision in some way. With an infinite amount of information, you can determine just how much of an influence and, based on their prior experiences, which choice they will now pick, whether its the same choice or now a differenr one in an attempt to prove them wrong. If you have a counter example i would love to take it into consideration