I think most people are scared of breaking something, if they're sensible. I know a couple of people who aren't scared to 'try' anything and the result has been a semi-burned down apartment (I can do my own wiring!) and a new set of dining furniture (I can sand it down myself!).
I think that the fear that people tend to have is from ignorance though. I'm trying to learn about being my own atuo-mechanic; I'm teaching my father more about the computer. What people maybe don't realise is just how hard it is to break a computer permanently. This is one of the biggest factors in people being poor with computers; I think that another is that there is often no clear indication of partial success, which is pretty discouraging for an adult who is starting to learn.
Sadly this is not always the case; I once broke the xfce version of Ubuntu within 10 minutes of installing it by playing around with the configuration options.