Double door: Is there gold in the zombies’ stomachs?

He obtained a double portal and traveled to a doomsday world. He was struggling to survive in the doomsday world, but he unexpectedly gained supernatural powers. He also discovered that this doomsday world was not as terrible as he had imagined. Here, except for the beast core, gold, gems... were discarded by the natives! But he could bring them back to the real world. At the same time, genetic drugs, powerful crystal cores... could all be brought back to the real world. By constantly traveling between the two worlds, he brought the wealth and technology of the doomsday world back to the real world. He stood on the top of the world! ...