People don't used to trust in new things or in things that they don't know. Moreover when people discover a new technology most of time it's thanks to the medias and we all know how the media can be idiots about the informations they gave to people. I speak about this but are you sure that "people fear about bitcoin" ? I am not sure
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)
About people who understand the technology they can be afraid of the vollatility, afraid to lost what they have so they prefer to not invest.