The benefit that Photoshop has is familiarity and Adobe's pricing structure is that of an abusive monopoly - they know they can charge as much as they do because they have a monopoly. This monopoly was earned in large part because early on, Photoshop was the most accessible app.round about 5.0 Adobe started to get sloppy.

I've started using Pixelmator for about half the image work I do on the Mac and IMHO it represents excellent value for money. It works like Photoshop used to do. It's lacking some feature, mainly the ability to work in colour channels, but for the price, it's hard to beat.

First of all, it is surprising because people put themselves at risk of fines or even jail by using unlicensed copies. If you don't like paying that much for software, then don't freaking use it and search for something cheaper. You don't freaking need all that functionality. Students and schools also get discounts. The many unlicensed copies out there are not used primarily by students. Also I worked for Adobe and I can tell you that they don't like piracy. That's one reason why they are moving towards a subscription-based model.

The difference between Gimp and Photoshop is that while Gimp gives you all the tools you need, it doesn't have an idiot mode, so it expects of you to know what you're doing.

A good example I can think of is Smart Sharpening. I don't know why the Gimp devs haven't implemented it. Maybe there's a patent on it or maybe they considered that it isn't worth it. Well, you can do it manually [1] ... it has the downside that it isn't something you can do in 3 clicks, so messing around to see how it looks is a little painful. On the other hand doing it manually makes you understand the process and allows you to have fine grained control, leading to better results, because truth be told, Photoshop has no way of knowing which edges are important in a photo and which aren't, so the results are not optimal.

This does scare beginners away and I wish that they implemented a nice wizard for what is standard functionality. On the other hand, it's actually quite easy to script such a wizard for Gimp in Python. So GIMP is designed for people that bend their tools to their will with a sharp inclination towards developers. It's not a good design because it prevents mainstream adoption, but for me it's like a breath of fresh air.

[1] http://www.gimp.org/tutorials/Smart_Sharpening/