looking for a proverb regarding defeat of man
Solution 1:
"It's the things we love most that destroy us."
I don't know the original source of this, but a quick Google search shows that it was used in Game of Thrones:
"The things we love destroy us every time, lad. Remember that."
(Source)
And in Hunger Games:
"It's the things we love most, that destroy us."
(Source)
My guess is that the saying is older than those books though.