Why does anyone need to think about security? Well, because some people does not respect your privacy, but then you can argue that everything that you put on the net or in the perifial is public knowlegde.
I'll argue that everything is public, since the Internet was created to share information and not hide it... if you can argue agains that then please let me know!
I'll also argue that privicy is of importance, since some information can be used to do harmfull things... like use your bank-account for one, impersonate you, etc. etc.
All that you can do with your own information, someone else can also do with your information - excpet perhaps "use your wife"
A little word of advise - don't use software you don't trust, need or know what is.