Meta-level: the fact that 1-boxers walk away with more money on average is ~explicit in the problem statement. So if you know that 2-boxers exist, but you’re surprised to see 2-boxing coexist with acknowledgement of the fact that 1-boxers walk away with more money on average, then you’re probably modelling 2-boxers wrongly.
Object-level: some 2-boxers reject compatibilism. To the extent that their choice is deterministic and fully predictable, they don’t see it as an exercise of free will. The argument runs something like:
If determinism is true, then the two possibilities are [I 1-box and the history of the universe and laws of physics are such that I inevitably 1-box] and [I 2-box and the history of the universe and laws of physics are such that I inevitably 2-box].
I definitely can’t freely choose what the history of the universe or laws of physics are.
So, if determinism is true, then I don’t have a free choice between 1-boxing and 2-boxing.
So they decide that the possible world in which they are perfectly predictable is irrelevant. To whatever extent they do have free will, they will exercise it to take the extra $1000.
This is only relevant given (at least) three assumptions, one about conscious experience and two about aggregation:
Being tortured for a long time and ‘tortured’ for 100ms differ only in length; there’s nothing in the experience of eternal (or very long) torture that distinguishes it from an infinite (or very large) number of isolated 100ms ‘tortures’
Good is separable (in the sense used by Broome) across time
Good is separable across people
If you’ve engaged seriously with this issue and are willing to write out an argument demonstrating that mine is a confused position, I will happily read and consider it! If not, I think you’re confusing “confused” with “disagrees with me on something I feel is obvious”.
(My position does require me to bite some actual bullets. But so does yours, and unless you’ve thought about this carefully enough to write about it for real, I suspect you’re underestimating how difficult it is to avoid all three of contradiction, vagueness, and weird/counterintuitive conclusions.)