By the same logic, why did NVIDIA released the GTX950 now at $159 ??? AMD Pitcairn was released almost 3 years ago, R7 270X was released 2 years ago
If AMD believes there is a market for the Nano at $499, it doesnt mean it can be recommended by everyone for everyone. There are people that will buy such a product, like there are people buying $1000 titans or upgrading to GTX980 over GTX780ti.
Just because you dont like it or you find it expensive doesnt mean everyone else thinks the same as you or has the same hardware need or what ever.
Also, i dont see AMD trying to capture a marketshare with those high-end, low volume GPUs. They sell them at the price they believe they should, same price as the competition. If someone is in the market for a $450-500 GTX980 today, they now have two more alternatives, the Fury and Fury Nano. Each one of the three has its own pros and cons, but you have three choices now instead of one.
Simple as that