The Last of Us: Did Joel make the right decision? (Spoilers)

[VAMatt]

Joel didn't doom humanity. There was no guarantee that sacrificing Ellie would have lead to a cure.

If it were a sure thing, or even close to it, then I would say he should have let her go. But, who would let a loved one die on the off chance that her death might lead to a cure? Probably next to nobody.