Okay it's weird but the first thing that came to mind. Logic: if I can think of a monetisable, nefarious application in 10 seconds, then it stands to reason that very many nefarious applications would be possible with more time/effort.

Not just possible, currently being implemented. People are murdered every year using this information. Last year a US politician was assassinated by someone who tracked them by buying this information from aggregator. You thought of a tame use case!

Which politician? I want to read more

https://en.wikipedia.org/wiki/2025_shootings_of_Minnesota_le... search for 'data broker' in page. Nightmare world we live in.