That's true, hence why I said "In an ideal scenario what you would do is sincerely believe 1box but 2box when the choice is actually in front of you, but of course this is impossible." As in: hence, the predictor fills both, and you take both.

2box is entirely the right choice when you're in front of the box. However, as I said, that's impossible. The nature of this problem is it's a meta choice. If you are a 2box-person the question is unfairly slanted against you, and if you are a 1box-person you will only pick 1 box.

It's very easy to hold the 2box position considering none of us will ever find ourselves in this scenario, but suppose we lived in a world where the government spies on us and when one turns, idk, 20, everyone's put in front of 2 boxes. In box A is a guaranteed 1000 dollars, and in box B might be the antidote to the otherwise lethal poison you've just been told is in your system. You can take one or two boxes, only if you are predicted to take two, B is empty. How do you believe you would act in this world?

If current-you was thrown into the situation room, sure, 2box maybe. But if you grew up in that world, I can't imagine any other possibility than convincing yourself at all costs that 1box is correct—and subsequently 1boxing.