Because:
(1) I don't have to deal with "Product Activation" and other pointless nonsense that makes customers jump unnecessary hoops.
(2) I'm not forced to upgrade my hardware with every new version of the OS.
(3) I do NOT need a DirectX 9-class video solution to have eyecandy.
(Linux users, see Compiz/Xgl that is developed by Novell. This eyecandy even works on a REALLY OLD Geforce 256!)...Check OpenSUSE, Ubuntu "Drapper Drake" and Gentoo wikis.
(4) I become a knowledgeable user. I learn something new everyday. I don't become a no clue fool, blindly clicking crap.
(5) I become self-sufficient. I don't have to wait for some multi-billion dollar company to get off its fat ass to bring a patch in. (over 7 days...Bad).
(6) I like the choice and flexibility.
(Can you build a file/print/scanner server and share it to Windows, Linux, Solaris, BSD clients for no cost on the software side?)
(7) I like the security features I can add on...SELinux, RSBAC, grsecurity, etc
(8) I like how Linux handles memory better than Windows.
(9) Because Microsoft rather give you band-aids like Windows Defender, and create money making schemes (upcoming Windows OneCare Live), than actually solve the root cause of Windows's security issues.
(10) When something crashes in Linux, I still have ways to recover and find the cause of the issue in logs. On a Windows box, we get some obscure message that's logged.
(11) It still allows me to play CNC: Red Alert 1 and 2 (via WINE)
(12) Why not?
To the vast majority of people Windows is free also. Also it comes pre-installed on their computer.
Here in Australia, Microsoft charges $120 to $140 per licence of Win XP with every notebook bundled with it. Microsoft makes it so people THINK its free...Its not. $140 Aussie Dollars may not seem like much...But you soon realise you can get 1GB (2x512MB) for that price!
Facts
* A large number of people have never heard of Linux.
* If they have, it is automatically assumed that its super HARD. A modern day desktop distro isn't hard to install and work with. The actual hard part is for the newbie to prepare before he or she installs or tries ANYTHING. Preparation is the KEY to a successful transition.
* If you walk a newbie carefully through Linux for a few hours, you realise anyone can use Linux. I have helped countless numbers of others who don't know where to start. But it also depends on the person...Does he or she really wanna switch? Are they sufficiently interested in putting effort in?
* No OS is perfect, but the general trend is that more technically inclined folks are looking for alternatives outside of Windows. (Besides, when Vista is mentioned with DRM, alot of people start to freak out). Just look at people illegally acquiring OS X and installing it on non-Apple hardware! There is a demand from the people around the WORLD for a Windows replacement!
* The biggest issue is that newbies expect all OSs to work like Windows. When they try Linux, it won't meet what they need, and they go running back. This has been proven countless times with blogs over the web and forum experiences.
* Linux's biggest sore point is that both hardware manufacturers and game companies who don't see a market for the Linux Desktop. ATI is a clear example of this. Their official response of the lack of quality drivers on Linux is because its a small market, not a money maker. (As a result, it costs them potential sales, as people will start using someone else's hardware if they ask about Linux. The general response from experienced Linux users is that ATI's Linux support sucks).
* There are however, companies that acknowledge Linux exists and provides drivers (binary or soruce form) or the necessary info to reverse engineer one. (Nvidia, HP, Ralink Technology, etc).
I guess, its really a number of factors. But in the age of where companies are sueing their potential customers and threatening other legal action to stop P2P, and the infamous (yet dreaded) DRM is ever approaching to the mainstream...The only thing left is really the choice of OS. It what you do right now that makes the difference for your computing future.
You can either put in the effort to switch away, or be forever trapped in Microsoft's vicious circle of "Let's see how much money we can extract from the customer today?"