I believe that is easily explained by AM making much more and way easier money by selling the blades than by mining with them. They can sell them at a price that never sees ROI (for whatever strange reasons buyers have).
They can only do this because they have no competition, literally none. This behaviour will not survive this year, I'm 100% sure. Future miner sales will be at competitive prices when the different mining companies (including AM and LC) will have to battle for their customers. It will be interesting to watch how far down they can and will go with their prices before it's again more profitable for them to mine themselves.