It's exactly what you'd expect from a low-friction, highly competitive marketplace. They eat everyone's profit in a hurry. That Apple was able to take a 30% cut while this happened leads me to believe they did an incredibly good job of creating a low-friction, highly competitive marketplace.

Now, contrary to econ 101 thought experiments, you don't always want to approach the ideal of perfectly-competitive marketplaces too closely. It can be bad for overall market health and even, ultimately, harm choices available to consumers for exactly the reasons cited.

[EDIT] actually it could also indicate that they've done one part of market-creation really poorly, which is that they're making reliable information other than price way too hard to discover, though again, that the market has not just survived this defect/cost but thrived indicates they did an uncommonly good job at other parts.