In Pascal's original wager the 'risk' is 50% . Due to our natural tendency to see two alternatives, once presented in A vs B form, as closer to even odds when information is absent. That's what wager is about - screwing up probabilities in absence of knowledge of how to calculate them, and arguing that it is quite probable when it's not quite probable.
Er. We're talking about Pascal's wager, right? The one published in Pensees? The one which explicitly invokes infinities, where it doesn't matter if the odds are 1 to 1 or 1,000,000,000 to 1, the argument still goes through?
Nick Szabo on acting on extremely long odds with claimed high payoffs:
Beware of what I call Pascal's scams: movements or belief systems that ask you to hope for or worry about very improbable outcomes that could have very large positive or negative consequences. (The name comes of course from the infinite-reward Wager proposed by Pascal: these days the large-but-finite versions are far more pernicious). Naive expected value reasoning implies that they are worth the effort: if the odds are 1 in 1,000 that I could win $1 billion, and I am risk and time neutral, then I should expend up to nearly $1 million dollars worth of effort to gain this boon. The problems with these beliefs tend to be at least threefold, all stemming from the general uncertainty, i.e. the poor information or lack of information, from which we abstracted the low probability estimate in the first place: because in the messy real world the low probability estimate is almost always due to low or poor evidence rather than being a lottery with well-defined odds.
Nick clarifies in the comments that he is indeed talking about singularitarians, including his GMU colleague Robin Hanson. This post appears to revisit a comment on an earlier post:
In other words, just because one comes up with quasi-plausible catastrophic scenarios does not put the burden of proof on the skeptics to debunk them or else cough up substantial funds to supposedly combat these alleged threats.