For instance, Nate buys a lot of jewelry. But he's not actually buying a ton of jewelry. No, he's an engraver, and it's just easier to buy the piece of jewelry, engrave it, and sell it. That being said, I don't even RP that he's an engraver. The diary is not the real story.
If you're super curious, feel free to ask an OOC question. If your character is just getting to know mine, then ask in character. Though... I don't know how your character would know, since I already said it's not public knowledge.