Sell some pills, dude, if you need money. It's like Yang Kai has forgotten he can sell stuff, ever since he forbade the Dragon Cave from selling anything. It's such an idiotic decision from the author, all for the sake to make the MC have so limited budget it keeps hampering him at every turn. It almost reminds me of the Japanese obsession with destitute heroes. Normally xianxia makes the MC gain money quite smoothly, even if they always spend money aggressively as well. When they ascend to a higher realm, they naturally will be poor again until they understand the new system and can again make loads of money. But here the author just decided the MC refuses to make money for no particular reason but still complains about not having it. It's so illogical that it's exceedingly strange the author doesn't see the problem himself.