I'd argue that there always must be something else at play in addition to greed. Greed is a given and the driver of the economy. Companies don't suddenly decide that maybe they should increase profits. So it's imperative to understand why they were able to increase profit margins without competition taking their market share. IMO that tells us what intervention is needed. The ideal market is companies at a constant knife fight with each other.
I'd argue that there doesn't have to be any secret reason. You say that greed "is a given" as an argument that there must be something mysterious going on, but raising prices when you can get away with it is no less a given.
The mystery is why you can get away with it. Bezos famously said "your margin is my opportunity". Why is there no Jeffrey Bezos waiting to pounce on the opportunity?
