Exactly, and this is also the reason many people are still using IE6. If your computer does the things you want - sends email, browses your favorite websites, lets you write a letter, maybe plays music - then what's the point?
Until recently, Apple's market has indeed been these "straw-man fanboys" - people that will always upgrade to Apple's newest kit, covet their latest OS or shiny thing. But that's not the case any more, and Apple have been selling to the common man, and they're eventually going to get bitten by the same bug as Microsoft - consumer apathy - as their market share rises.
I have a Macbook running Tiger, and a PC running XP. The only OS I regularly upgrade is Ubuntu, and only then because it's (almost) automatic.
There is a perception among Windows users that you don't "upgrade" Windows. You get a new machine with a new version of Windows, and then you spend a lot of time trying to get all of your files moved over and your programs working again. And then, after all that -- the user interface looks different. Things have moved around. You'll have to spend some time learning how to use your computer again.
Meanwhile, the perception among Apple users is that they can put in a disk, run an installer, and they get to upgrade their old hardware to run the new thing. There might be a few user interface differences, but most of them are subtle. They don't have to learn how to use their computer all over again, and somehow it's better now.
In both cases, the perception isn't quite reality, but that doesn't matter. Those perceptions are both Apple's strength and Microsoft's weakness in the vast majority of their markets.
Essentially Mac users get used to the upgrades, which are much more incremental, fairly painless, and much cheaper. Mac OS X also seems to actually get faster (Quartz Extreme, launchd, 64bit+LLVM) with every major release, rather than slower.
Until recently, Apple's market has indeed been these "straw-man fanboys" - people that will always upgrade to Apple's newest kit, covet their latest OS or shiny thing. But that's not the case any more, and Apple have been selling to the common man, and they're eventually going to get bitten by the same bug as Microsoft - consumer apathy - as their market share rises.
I have a Macbook running Tiger, and a PC running XP. The only OS I regularly upgrade is Ubuntu, and only then because it's (almost) automatic.