"probably" doesn't lead to "yes, it works". What's the tradeoff? How many good actors does "probably" imply?
It is trash, but at least it is something.
Compelling arguments in favor.
5%? Nah, I'll pass; I don't want to spend my last six months in agony, so it's not worth it (i.e., bad trade-off). 95%? Hell yes, sign me up. Your own analogy supports what I said earlier.
On a side note, the statement "Chemotherapy will probably cure your cancer" is also not true and shows a bit of ignorance re cancer therapies in general.