When do you think computer security should be applied or needed?
If a computer ever receives data from any source outside the
computer or provides data to an outside recipient - computer
security is needed. Since that includes the operator at the
keyboard, that means just about every computer needs security. A
few devices that have internal computers built into them which
receive no outside data and supply no data outside of the device
MIGHT get away with no security - but even there some security
would be prudent to prevent malicious reprogramming of the internal
computer.
When computers were being developed, the main goal was just to
get them to work, not to make them "secure". As a consequence there
are a lot of avenues to attack computers. The question is not so
much IF a computer needs security - it is more a question of HOW
MUCH security the computer needs. The degree of security a computer
ought to have depends on how valuable the information on the
computer is, how critical it is to protect the information from
being divulged to unauthorized persons, how important it is that
the information remain unaltered (You don't want errors in the data
in the computers of the bank where you have an account), how
important it is to be able to prove someone sent or received data
(for example you want there to be proof that you sent your
electronic payments and for the recipients to not be able to deny
that they received them), and how critical it is to be able to get
data into a computer or out of it when you want to (Any student who
had their computer crash just as they were about to print out their
term paper can sympathize with this one - just knowing the paper is
stored on the computer doesn't help you if you can't get it out. If
you include computers that run life support systems, you can see
that there are even more critical systems that need to be protected
such that they continue to function no matter what).