Computer users invest their own time, concentration, and patience - on top of a not-inconsiderable amount of money - in getting their computers and learning how to use them for their purposes. It is human nature to be reluctant to conclude that they have made a mistake in a purchase into which they put that much - so, paradoxically, the more reason there is to believe that they have made a mistake, the more resistant to reality they become. It's also human nature to believe that what works for you should work for everyone else, and people can be reluctant to admit that not everyone needs or wants what they have, and that it's rude to immediately assume should, and that they screwed up because they didn't.