It's not because of lack of knowledge, it's because of lack of will to learn that knowledge.
The best you can do is try to explain them what it's all about, but if they only hear "it'll be cheaper that way", then it's their fault.
Fact is, they are making an uninformed decision, that has nothing to do with not being a geek or a nerd. But with some common sense.
You can't drive a car and not check your brakes, isn't that an obvious technicalitie? Well yes, but if you don't do it, you might die. Just like if you don't pay attention what laptop you are buying might drop you out of college like that girl.

Just like there are design courses that require an Apple Notebook, but buying an Apple is expensive and it has an unfamiliar OS. So I'll just buy a cheap Dell Laptop with Windows, but then I can't do anything with it for the course, because it's not an Apple Notebook! Oh stupid Dell and stupid Windows, you've ruined my life, it's all your fault!