99% is tough for various evolutionary theoretic reasons, but another bubonic plague is a hell of a lot easier.
These things are more dangerous than nukes. Any technology for creating GMOs should be regulated and licensed for the same reason that we regulate and license fissile material. This should remain true until and unless we can stop killing and hating each other and until a decade goes by without some nut opening fire on a bunch of kids in a church.
That guy can now order a CRISPR kit.
The people who hang out on 4chan /pol and "pray" for ebola to go airborne so it will de-populate Africa can mail order a CRISPR kit. It wouldn't be the dumbass meme-slinging shitlords. It would be that one lurker with a bio Ph.D and a shrine to Adolf Hitler and a collection of books by Julius Evola and the Protocols of the Elders of Zion all full of highlighting and underlining.
"He was just kind of quiet. Seemed nice. Said hi to the neighbors. He spent a lot of time on the Internet and got a lot of FedEx packages. Saw him come and go at night a lot."
"Police say the suspect tested the pathogen on human victims to perfect it. He took his victims mostly from homeless camps or hired prostitutes. A mass grave has been discovered on a remote property owned by the suspect and meticulously catalogued tissue samples have been found in a storage locker..."
"The disease's lethality was increased by the suspect's attempts to make it fatal only to certain ethnic groups as the inclusion of human antigens causes a reaction similar to that experienced by organ transplant recipients..."
"Officials say they can't provide a time-table for how long the quarantine will last. The army is being mobilized to deliver supplies..."
... then a few weeks later just the tone and a scrolling message ...
https://www.youtube.com/watch?v=3HlP2GHn_Ck
I have children. Ban this stuff right now.
Edit:
I just picked a contemporary motive. There's an endless supply of wills-of-God and causes "that will not be understood now... but history will judge me..."
