Ok, but both the HD2000 and the HD3000 series were pants. Prior to the HD4870, the GTX 8800 was the top performing single GPU. It came out in summer 2006, the HD4870 was summer 2008. The HD4870 retailed for £200 on launch, which actually undercut the GTX 8800 by some margin at the time, whilst outperforming it by about 30% - 40%.
And important to note, is that the Titan only outperforms the HD7970/GTX680 by about 20% - 30%, with the Radeon R9 290X set to do just about the same. As things stand, someone living in UK can buy approx 4 HD7970's for the price of one Titan or three R9 290Xs.
Madness. Especially since current 1080p gaming really and truly doesn't demand the extra juice, unless we were getting picky to the point of psychological illness.
But a fool and his gold are soon parted, no doubt there will be queues of people lined up for these and stocks will soon be depleted.