Your thinking is based on flawed assumptions. Nobody is forcing Aichan to talk to them. If the fan is spending that kind of money, I'm sure Aichan knows them well and is happy for their support. I'm sure she talks to them gladly. If Aichan ever feels uncomfortable she can tell staff and have them kicked out even banned, no matter how much they spend. Our oshis love talking to us. I know idols who hold their own talks outside of their groups just because they want to talk to fans more, or solo artists like Naachan who hold talks because she wants to.