There is a lot of human psychology at play here which I find interesting. The fact that people are willing to pay above-face-value for these tickets implies that there IS a market for them, and so it means the face value is underpriced.

However, if the original pricing was indeed the high price at which the market cleared, people would consider it as greed on the artist's part. So we end up in this bizarre scenario where people are happy to overpay a faceless middleman for watching an artist rather than pay the artist themselves.