Once an idea is learned, once it settles in, it becomes comfortable and hard to discard, like an old hat. And trust me, I have many old hats. Some I haven't worn in years, but I still keep them. Emotion gets in the way of practicality. By virtue of time spent, even ideas become old friends, and if you can't bear to lose an old hat that you never wear, imagine how much harder it is to abandon ideas you grew up with.