I've often had half-finished LW post ideas and crossed them off for a number of reasons, mostly they were too rough or undeveloped and I didn't feel expert enough. Other people might worry their post would be judged harshly, or feel overwhelmed, or worried about topicality, or they just want some community input before adding it.
So: this is a special sort of open thread. Please post your unfinished ideas and sketches for LW posts here as comments, if you would like constructive critique, assistance and checking from people with more expertise, etc. Just pile them in without worrying too much. Ideas can be as short as a single sentence or as long as a finished post. Both subject and presentation are on topic in replies. Bad ideas should be mined for whatever good can be found in them. Good ideas should be poked with challenges to make them stronger. No being nasty!
It's a little too strong, I think you shouldn't give away the $100, because you are just not reflectively consistent. It's not you who could've ran the expected utility calculation to determine that you should give it away. If you persist, by the time you must do the action it's not in your interest anymore, it's a lost cause. And that is a subject of another post that has been lying in draft form for some time.
If you are strong enough to be reflectively consistent, then ...
You use your prior for probabilistic valuation, structured to capture expected subsequent evidence on possible branches. According to evidence and possible decisions on each branch, you calculate expected utility of all of the possible branches, find a global feasible maximum, and perform a component decision from it that fits the real branch. The information you have doesn't directly help in determining the global solution, it only shows which of the possible branches you are on, and thus which role should you play in the global decision, that mostly applies to the counterfactual branches. This works if the prior/utility is something inside you, worse if you have to mine information from the real branch for it in the process. Or, for more generality, you can consider yourself cooperating with your counterfactual counterparts.
The crux of the problem is that you care about counterfactuals; once you attain this, the rest is business as usual. When you are not being reflectively consistent, you let the counterfactual goodness slip away from your fingers, turning to myopically optimizing only what's real.