Picked up a Wasteland World

In an accident, Li Nan traveled to an apocalyptic world. The world is in a mess, with wastelands left by war everywhere. Food cannot be cultivated, water cannot be drank, and even the air cannot be breathed. Things that were once common have become expensive. Once expensive jewelry, gold, and even the technologies and talents that changed the world have become cheap. A bottle of cans and a bottle of water can make the stingiest people give their treasures without hesitation, and the most timid people pay their lives. While feeling emotional, Li Nan discovered that this seemed to be a business opportunity for him who could travel through two time and space...