While using the nuclear technique, he thought about his next course of action. At this point, his plans of earning nuclear energy by going to the blood volcano and killing monsters was suicide, delaying his plans for upgrading his combat tactics.
Therefore, he could only think about other ways to earn nuclear points. Stealing from Envoys is plausible, but once caught, there is no way he would lucky enough to survive another Envoy's barrage.
Apart from doing the academy's mission, perhaps the only way was through creating nuclear weapons. It was expensive to get the materials but was even more expensive to buy a nuclear weapon, about ten times more expensive.
The gains were obvious. He could buy materials worth a thousand blood points and sell them for ten thousand blood points. Obviously, he would create only basic weapons.