Bioweapons are increasingly more likely to be the end of humanity. With fancier tools like CRISPR you're getting closer and closer to having one person in a basement making something that can propagate across the whole world. Nuclear weapons are inherently limited by the fact that you need huge institutions to generate and deliver large numbers of them, and without large numbers of them you can't destroy humanity because of the large size of the planet.
https://cco.ndu.edu/Portals/96/Documents/prism/prism_4-4/Str...