I guess I should add why I'd like such a BOTEC: I'm broadly skeptical that anti-abortion interventions will turn out to be competitive with animal welfare interventions on a cost-effectiveness basis under the assumption of foetal moral patienthood, given that my impression is that animal welfare has a vastly wider scale (perhaps with exceptions like choosing to not have an abortion or voting for your polity to criminalize abortion).
FWIW I would have appreciated a BOTEC for the cost-effectiveness of various anti-abortion interventions (under the assumption of the wrongness of abortion). You gesture that it's possible to affect the number of abortions via policy, but this is obviously a pretty limited analysis. Absent this sort of BOTEC, this reads as a case for policy-makers to restrict abortion, rather than an effective altruist case for pro-life/anti-abortion advocacy, as your title promises.
Aum intended to kill thousands of people with sarin gas, and produced enough to do so. But they a) were not able to get the gas to a sufficiently high level of purity, and b) had issues with dispersal. In the 1995 Tokyo subway attack, they ended up killing 13 people, far less than the thousands that they intended.
IIRC b) was largely a matter of the people getting nervous and not deploying it in the intended way, rather than a matter of a lack of metis.
(1) Sorry, I was copy-pasting the formula in the spreadsheet, but missed the extra 0.1 factor you added at the end. First of all, I still think the factor of 50 you're shaving off due to diminishing marginal returns seems quite extreme, given the lack of articulable justification for why it should be so big. I guess the extra factor of 10 is because diet cola exists? I'm not sure why you're adding that - as I mentioned, the questions you asked people already mentioned that people could substitute to diet sodas. Quoting from the instructions to participants of cell E1 of your survey spreadsheet, "Note that this does not include artificially-sweetened beverages (i.e. Coke Zero, Diet Pepsi, Sprite Zero etc) – you would still be able to drink those.".
(2) Makes sense. Regarding composition, we could look at polling of soda taxes to get a sense for this. One thing to note is that politicians typically don't implement these taxes (hence you looking into lobbying for them), suggesting that they're not very popular. Of the two polls I could find, it seemed like either there were no significant differences between groups, or that Republicans were more opposed to soda taxes than Democrats. Given that the vast majority of American EAs are Democrats, this suggests that the poll could be underrating the disutility of reduced sugar consumption.
(3) Note that many of these factors go both ways - people could be motivated to appear self-abnegating and healthy, think sugary drinks are less healthy than they are (anecdotally, I've asked two people how much diabetes would be reduced if sugary drinks didn't exist, and they both overestimated relative to your cited number), or not think about how sugary drinks are actually OK. It's indeed plausible that people value their future selves less than they ought to according to standard utilitarianism, but I don't think it's a priori clear that they do so by a massive factor.
Beyond potential a prior scepticism as to whether such a significant number of people not dying or suffering ill health from diabetes really is less valuable than loss of freedom to drink sugar drinks
I guess I want to add something here about why one would have the opposite prior: by and large, a decent model of people is that when they make decisions, they roughly weigh costs and benefits to themselves (or follow a policy that they adopted when weighing costs and benefits). Diabetes is mostly a cost to oneself. At least in the US, people are broadly aware that drinking sugary drinks makes you a bit less healthy, via an increased chance of obesity, diabetes, heart disease etc. But people drink them anyway because they're tasty - that is, in their judgement, the value of being able to drink them is higher than the health risk.
It seems like you have a strong prior that people are wrong about this, and that they significantly underweight the health impacts of soft drinks, such that limiting their intake by 20% is worth it to reduce their risk of getting diabetes by 1%. This isn't impossible - it could be that people don't know that sugary drinks are unhealthy (of course, people could also overestimate how unhealthy they are), or that socialized healthcare means that there are massive externalities to diabetes cases - but I didn't see any arguments to that effect in your executive summary.
Then, using the y=x^0.1 formula, we take (1-d)^0.1 to find that 98% of "freedom of choice" still remains, and correspondingly, there was a 2% reduction.
The number in the sheet is a 0.2% reduction, not a 2% reduction. [EDIT: my bad, it's a 2% reduction, there's just another factor of 10 reduction that I mistakenly lumped into that]
In my experience of being an Australian, "fag" is not a common term of endearment I've encountered, except in the sense that general insults are used as terms of endearment (like "shit-for-brains" etc).