I see your line of thinking more aptly applied to Microsoft. The people I have talked to use their technology for one of 4 main reasons (these are things people have actually said to me, except for number 4)-
To play devil's advocate...
1. They perceive it as cheaper than other technologies (arguably correct in some instances).
I'd say this isn't just some instances, that in fact it's most instances. While there are examples of rough parity between Mac hardware (27" iMacs, Mac Pros) and PC hardware, the difference in cost essentially grows greater as the weeks go by, since Apple continues to charge the same price for hardware introduced several months before, whereas PC companies have typically long since updated the model line since then.
Then you have systems like the Macbook, MacBook Pro, Mac Mini, etc., which, while nicely designed, are generally far more expensive than equivalently-spec'd PC counterparts. You end up essentially paying anywhere from a few hundred to seven hundred more for the right to use OS X and possibly a sturdier (to various degrees) chassis.
2. That is what they use at work (and how that affects their home usage still confuses me)
That can be fairly easily explained. You use what you've become comfortable with. People on here like to complain that Windows is some horribly unstable, ridiculous piece of software, but in terms of instability, that hasn't really been true since the 9x kernel era. Sure, you can still crash Windows... just like you can crash OS X, Linux, Unix, etc. The biggest complaint is the issue with virus', and a just one at that. However, free antivirus programs essentially take care of that, and do the job well.
Thus, it goes back to being what someone is comfortable with. Or maybe they'll want to do some work from home, and thus need software compatibility (there's obviously the fact that there's much cross-platform interoperability and compatibility, but most people aren't knowledgeable enough to know that, and so would prefer their home system to be "as similar" to Windows as possible). Remember several months ago when the vast majority of Mac owners also were running a Windows system in the household? While a lot of those were bootcamp, it still shows that even Mac users feel the need to keep Windows around for various reasons. How many people feel the need to keep OS X around?
3. They don't like change, and changing to a different technology sounds scary
Kinda touched upon it above, but why fix what isn't broken? If someone is comfortable and content with using whatever OS they have, they shouldn't *have* to change.
If anything, I think the above line is really only applicable (with regards to the idea of being "sheep") when it involves someone who refuses to give up their existing platform, even when a newer one will do everything they do better and is clearly superior. Possibly also when they continue to defend a product to any length, without a legitimate argument to stand upon (besides "it's simply better").
So the above line about change, could arguably apply to PC fanboys, to Mac fanboys, to console fanboys, etc. etc.
4. They are technologically illiterate enough to think they have no other alternative.
Eh, most people are knowledgeable enough to know they have a "choice", but the technological illiteracy often comes in with respect to knowing what the differences between those choices are.
A good example would be the "Megahertz Myth" era, when Intel was trying to get customers to believe that a faster processor was always the superior option, while AMD was pushing that there's more to a processor than solely speed.
Ultimately that myth began to die out once the Athlon 64s began to trounce the Pentium 4s at much lower speeds, and ultimately was put to rest when Intel themselves came out with a lower-speed but vastly-superior processor line (to a lesser extent the Core line, but primarily the Core 2 series).
But yeah, Apple and OS X is ubiquitous enough these days that I think people know it can be a legitimate option to Windows, or at the very least they know it exists and are willing to give it a shot.
So ultimately, I don't really see PC users as being "sheep", largely because most don't really care about Microsoft or what it does with Windows. If something better (to them) comes long, and they can change to it, they probably will...