A possibly interesting read would be about aliens who bring a cure for all illness, but unknown to use it also cures people of the need to get ahead of thier fellow human at all costs. Thus they stabilize the human race which then stabilizes the planet...
Something kind of adjacent to this happens in Octavia Butler's Xenogenesis series. Aliens come over to fix the Earth and humanity, but decide that human nature is part of the problem, and set out to modify it. It's a really interesting read.