We have more reasons now (nuclear weapons, unfriendly AI, grey goo, the great filter) to think we will someday destroy ourselves than people in 1900 did.
I don't believe that it is generally agreed upon where the great filter lies. We could already be past it. Finding multi-cellular life elsewhere in the solar system would support the hypothesis that the great filter lies ahead of us. But, we have not done that.
A blog post by Athrelon on More Right.