And I perceived you as being needlessly pedantic and choosing implausible interpretations of my words so that you could correct me. You'll note that your comment karma stands. I am, in fact, aware of quantum mechanics, and you are, of course, entirely correct. Coins behave in precisely deterministic ways, even if they rely on, say, radioactive decay. The causality just occurs in many Everette branches. That said, there is no way that before 'you' 'flip the coin' you can make a prediction about its subjective future state, and have more than half of your future selves be right. If that's not 'unpredictable' by the word's colloquial definition, then I'm not sure the word has any meaning.
You will notice that when I said that the coin is unpredictable, I did not claim, or even imply that the world was undeterministic, or that quantum mechanics was wrong. If I had said such a thing, you would have right to correct me. As it is, you took the opportunity to jump on my phrasing to correct me of a misconception that I did not, in fact, possess. That is being pedantic, it is pointless, and above all it is annoying. I apologize for rudeness, but trying to catch up others on their phrasing is a shocking waste of intellect and time.
EDIT: Again, I can totally discard every word that's entrenched in good, old-fashioned single-universe connotations, and spell out all the fascinating multiverse implications of everything I say, if that will make you happy -- but it will make my posts about five times longer, and it will make it a good deal more difficult to figure out what the hell I'm saying, which rather defeats the purpose of using language.
I'll note that I reject your 'implausible' claim, object to all insinuations regarding motive, stand by my previous statements and will maintain my policy of making mild clarifications when the subject happens to come up.
There seems to be little else to be said here.
Related to: Can Counterfactuals Be True?, Newcomb's Problem and Regret of Rationality.
Imagine that one day, Omega comes to you and says that it has just tossed a fair coin, and given that the coin came up tails, it decided to ask you to give it $100. Whatever you do in this situation, nothing else will happen differently in reality as a result. Naturally you don't want to give up your $100. But see, Omega tells you that if the coin came up heads instead of tails, it'd give you $10000, but only if you'd agree to give it $100 if the coin came up tails.
Omega can predict your decision in case it asked you to give it $100, even if that hasn't actually happened, it can compute the counterfactual truth. Omega is also known to be absolutely honest and trustworthy, no word-twisting, so the facts are really as it says, it really tossed a coin and really would've given you $10000.
From your current position, it seems absurd to give up your $100. Nothing good happens if you do that, the coin has already landed tails up, you'll never see the counterfactual $10000. But look at this situation from your point of view before Omega tossed the coin. There, you have two possible branches ahead of you, of equal probability. On one branch, you are asked to part with $100, and on the other branch, you are conditionally given $10000. If you decide to keep $100, the expected gain from this decision is $0: there is no exchange of money, you don't give Omega anything on the first branch, and as a result Omega doesn't give you anything on the second branch. If you decide to give $100 on the first branch, then Omega gives you $10000 on the second branch, so the expected gain from this decision is
-$100 * 0.5 + $10000 * 0.5 = $4950
So, this straightforward calculation tells that you ought to give up your $100. It looks like a good idea before the coin toss, but it starts to look like a bad idea after the coin came up tails. Had you known about the deal in advance, one possible course of action would be to set up a precommitment. You contract a third party, agreeing that you'll lose $1000 if you don't give $100 to Omega, in case it asks for that. In this case, you leave yourself no other choice.
But in this game, explicit precommitment is not an option: you didn't know about Omega's little game until the coin was already tossed and the outcome of the toss was given to you. The only thing that stands between Omega and your 100$ is your ritual of cognition. And so I ask you all: is the decision to give up $100 when you have no real benefit from it, only counterfactual benefit, an example of winning?
P.S. Let's assume that the coin is deterministic, that in the overwhelming measure of the MWI worlds it gives the same outcome. You don't care about a fraction that sees a different result, in all reality the result is that Omega won't even consider giving you $10000, it only asks for your $100. Also, the deal is unique, you won't see Omega ever again.