[EliRivers]

If it has no noticeable effect - my life is completely identical - it's hard for me to see it as something negative. If something has absolutely zero effect on my life whatsoever - not even a single advert on my screen - calling it a virus or malware seems unwarranted.

I suppose if my personal data was somehow used to damage someone else, that would warrant calling it malware.

[Zuider]

Your stolen personal data could be used to empty your bank account or to commit a crime in your name which could cause permanent damage to your reputation, even if you were exonerated.

[EliRivers]

That sounds like something I would notice, and is thus outside the scope of this discussion.