Janet Yellen isn't a powerful person because of her reputation on the speaking tour circuit. If you hire Beyonce it's because you're paying for the performance

Janet Yellen isn't a powerful person because of her reputation on the speaking tour circuit. If you hire Beyonce it's because you're paying for the performance she gives. If you hire Janet Yellen, no person credibly believes it's because that hour talk she's giving is hugely valuable. It's because you want to establish connections with her to influence her in her actual job where her power comes from. It's a pretext for paying her money that, were you to turn up to her office and hand it to her at her day job, would be a bribe.