The Chosen One began life as a tribal nobody trying to end a drought. But his belief in every man's right to freedom, regardless of radiation levels and/or mutation, eventually lead him to freeing the West Coast (or what remained of it) from the Enclave. All he had to do was murder the President of the Enclave (don't worry he was evil. Millard Fillmore-evil) and blow up an oil rig (an evil oil rig. Deepwater Horizon-evil). And with that, the people of the post-apocalyptic land no longer had to live in fear of the evil government just super mutants, radiation, starvation, dehydration, disease, raiders, slavers, radscorpions, poison, gangsters, thieves, ghouls, rats, and deathclaws. That's called "progress."