There is no such thing as computer security, in general, at this point in history.
Indeed. Why lock your car door as anyone can unlock and steal it by learning lock-picking?
That subtlety is important because it explains how the backdoors have snuck in — most people feel safe because they are not targeted, so there's no hue and cry.
Are they wrong? Do gradations of vulnerability exist? Is there only one threat model, “you’re already screwed and nothing matters”?
It's still worth solving one of these problems.