It's likely subsidized by the AT&T exclusive. I believe it's $200/month plus some contract. Which means they may be getting kickbacks totaling more than $200/device which would improve their margins. Or more interestingly, mean the device can be higher end and impress people more while at least not being a loss for Amazon. It's basically a store interface, leading to increased sales. Firefly is like Shazam for products, people will likely buy way more from Amazon.