A few years back I tried a trial version of Photoshop and although I could see why it was the market leader I could not see why it was 10 times more expensive than comparable software. In the UK CS6 was selling for over £600 although in the US it was 20% less. Now I'm looking at it through a yearly rental and after a few weeks that continues to be my viewpoint. I'm hoping that by the end of the year my view may have changed.
To answer my own question and to understand the poor performance/price ratio of Photoshop consider the following. A business user gets his 20% VAT refunded and as a business expense the tax man contributes to the cost of the software at the marginal tax rate of the business typically 30 to 40%. So the professional is only paying half the rate of the amateur. The main argument is that the staff already know how to use Photoshop and would lose time retraining on something else. In this way the high cost of Photoshop can be justified to the professional. For the amateur market it continues to look very poor value for money.
A similar situation exists for Microsoft with its cash cows of MS Office and Windows operating systems. Microsoft wants hundreds of pounds for systems which were adequate decades ago. Although as a hobbyist I like to keep ahead on the hardware and software fronts, at work I am using Windows XP and Office 97 and perfectly functional they are too. The problem with software developers is they want a steady income for problems which have been solved years ago. I wouldn't expect to get paid forever for work I did back in 2005 say but this is what they want. Under these circumstances you would expect the cost of upgrades to come down to match the marginal benefits of the latest software. And to some extent this happened. The introductory offer on Windows 8 was good value. Too bad people didn't like the software, mainly the Start menu replacement.