@ "Your CPU works quite nicely as long as you do not run untrusted code from www.shadyAdFlinger.com"
Really? so all the websites with bitcoin JS are doing it deliberately?
Since there is no really way to avoid all malware since it only gets detected once it is recognised and the OS assumes that the CPU is secure then unless your machine is completley isolated you are just as vulnerable.
That is may have the similar capablities to an obsolete super computer and is "only" $1000 is a meaningful as saying before cars existed then people had to walk and ignoring that the change has created new perils the old pedestrians never experienced. Things have changed and the comparison of just speed/cost alone is ignoring all the good and bad consequencies of that change, consequencies that make the speed/cost ratio irrelevant