But also you’re right that even a pretty good (but not perfect) predictor doesn’t change the scenario.
What I find interesting is to change the amounts. If the open box has $0.01 instead of $1000, you’re not thinking ”at least I got something”, and you just one-box.
But if both boxes contain equal amounts, or you swap the amounts in each box, two-boxing is always better.
All that to say, the idea that the right strategy here is to ”be the kind of person who one-boxes” isn’t a universe virtue. If the amounts change, the virtues change.