How do you know very little profit is made on the device by the carriers?
And no way they are paying that much for it.
I'm buying one device for $649 and the carrier makes a multi billion dollar commitment to purchase iPhones and gets a $49 discount

lol OK.
I can certainly say that resellers don't make much on Apple hardware (this is everything Apple makes, not limited to phones); the numbers are generally under 10%. Nobody really knows how much these units are purchased for, so it's all speculation. TMobile is essentially selling you the phone for $580, so I would suspect they are getting the phone that less than or equal to that number. In any case, pretty much all carriers push every other device known to man, and NEVER the iPhone, based on personal experiences, and other's experiences that I have read here.
At the end of the day, Verizon isn't losing out. But it's one of those questions of, how much money is enough? We vilify these carriers for making money. Then we have the company that makes the iPhone, Apple, that seems to get far less scrutiny. Their profit margins are pretty darn huge too, right? So what is it about Apple that makes it "more ok" for them to make a boatload of money off of the consumer, but a lesser boatload shouldn't be enjoyed by the carrier? After all, without the carrier(s) the iPhone would be, well, nothing.
I don't know the right answer to any of this. but I think it is easier to hate a carrier for the service you are paying for. It is not a tangible good. Once the month is over and you have sent them your check, you have nothing to show for it. With the iPhone (or any other) hardware, you have something to show for that small handful of Benjamins you had to let go to acquire it.
----------
And Tmobile sells it for $580 and still makes a profit? And finances it for free over 24 months without making a penny right?
As I mentioned in a previous reply, I don't claim to know numbers. But TMobile taking this "hit" is actually quite believable. Think about it. They are literally the last of the carriers in the US to get this phone. The pay as you go guys got the dang thing before they did! They want to get people onto their network in droves, as is evidence by the structuring of their plans. Again, I don't know their business model, but it is not uncommon for a company to run near or lower than cost in order to broaden the big picture for years down the road.
Do I believe TMO isn't making a dime on the handset, or even that they are losing money on them? I wouldn't be shocked either way. But I do know that the money they make on every other handset far exceeds the money they make on the iPhone.