I counterpoint it to the video game/visual novel Danganronpa which is a literal battle between Hope and Despair in which these emotions are held to be contagious.
Another is the musical "The Music Man" in which the "Music Man" is a huckster who brings out the talent latent in the community.
Interesting that the male lead of "The Music Man," (film and stage versions) Robert Preston, also starred in a film where he brings out the talent latent on Earth. In "The Last Starfighter" a huckster named Centauri places an arcade game in various places as a sort of "Excalibur" test to find twitch-game experts who could defend the Star League's Frontier against Xur and the Kodan Armada.
For your further pop culture enjoyment: fans of stories like these may enjoy a more modern version -- Ernest Cline's "Armada" shares many similarities. You might remember Cline from such films as "Fanboys" and "Ready Player One." I imagine "Armada" will get its own film adaptation someday.
I think I was first exposed to it in Ray Bradbury Theater form, and it’s very much stuck with me, the idea that we in principle could have a better world if we had more hopeful messages and weren’t fed what to think and what to allow and what to feel powerless against by the powerful.
(Although of course my interest is in honest hopeful communication and not fabricated "evidence".)