Well, the easiest would be a nice, survivable AI being built by people taking no safety precautions at all.
No, the easiest way to make your work irrelevant would be an event that set humanity back to a preindustrial level of technology. The easiest good event is a safe AI without safety precautions.
It's just occurred to me that, giving all the cheerful risk stuff I work with, one of the most optimistic things people could say to me would be:
"You've wasted your life. Nothing of what you've done is relevant or useful."
That would make me very happy. Of course, that only works if it's credible.