Francis, who received a boisterous welcome from tens of thousands of young people as he celebrated his first public Mass in South Korea, pressed his economic agenda in one of Asia's powerhouses, where financial gain is a key barometer of success.
The Pope took a high-speed train to the central city of Daejeon, where young Catholics have been meeting for the Asian version of World Youth Day.
In his homily, Francis urged the young people to be a force of renewal and hope for society.
He said: "May they combat the allure of a materialism that stifles authentic spiritual and cultural values and the spirit of unbridled competition which generates selfishness and strife.
"May they also reject inhuman economic models which create new forms of poverty and marginalise workers."
But his message will be a tough sell in South Korea, which has grown from the destruction and poverty of the Korean War of the 1950s into one of Asia's top economies.
Many link success with ostentatious displays of status and wealth. Competition among the young, especially for places at elite schools, starts as early as pre-nursery and is fierce. The country has one of the highest suicide rates in the world.
Francis said that in such "outwardly affluent" societies, people often experience "inner sadness and emptiness" and that this depair had "taken its toll".