In the End of the Galaxy, I Have Stockpiled Tens of Billions of Hydrogen Bombs

The protagonist accidentally activated the memory fragments of an ancient alien civilization and mastered all the black technology of the universe in an instant. He has since been able to control high-energy material refining, space interstellar navigation technology, planetary transformation technology, and the most advanced military weapons manufacturing technology. But he is cautious and low-key, knowing that if he is exposed prematurely, he will attract crazy covetousness and threats from all forces on the earth or alien civilizations.