"Some of them..."
Some of them, certainly. Are you honestly claiming that all or even most Apple users do so because of marketing if there's no quality product to back it up?
Edit: as per your post history/above, you appear to use Apple hardware. Just because of the marketing?
"HP through marketing."
Without a product behind it.
"Dell through design"
It is to laugh.
"MS through marketing/Zune/Pink."
Which might do something for them, as by all accounts the new Zune is decent, though with some of their typical tonedeaf touches (30-second ad plays before running an app? Puh-leease.), though their smartphone OS is still atrocious.
"Google through Android."
With their 7% marketshare to iPhone's 40% (numbers from AdMob, which is naturally not entirely representative of the smartphone market as a whole, but close enough for the purposes of argument.). And this despite Android's improved openess over iPhone OS and the wider variety of harder. Or possibly because of it... Only having one platform to develop for it certainly a massive competitive advantage for iPhone over virtually anything else out there.
"Video drivers and sound drivers are poor, sound quality is poor."
Considering that video/sound chips used by Apple are all (reasonably) commonly used hardware these days, Linux not having drivers for it is squarely the fault of the Linux community/hardware manufactures who don't provide drivers for them. Ditto goes for Windows, with the trackpad being the obvious exception there.