The Undead system - Chapter 57: lucky gamble

Over a million years ago, the first human contracted with the first Spirit. Ever since then, Spirit use has become commonplace. Humans used Spirits to carry items and start fires. Eventually, even start wars. Thousands upon thousands of years past and one day, one human did the impossible. He transcended his mortality and ascended to the realm above.

Wang Bin unexpectedly gained the ability to travel between the post-apocalyptic world and the real world. In the apocalypse, he organized a powerful team and continuously transported gold back to the real world.Using the gold from the apocalypse, Wang Bin built a commercial empire in the real world, eventually becoming the wealthiest person on Earth. His every word and action could influence the rise and fall of entire nations.At the same time, his development in the apocalypse was equally impressive.Through countless brutal battles, he ultimately established the largest and safest settlement in the dying apocalyptic world, making an extraordinary contribution to the survival of humanity.

What would you say is the most valuable thing in this world?