Because their personal information is public thus everyone has it which makes re-identification much easier. Although nowadays there's so much information out there that "famous" covers a lot of the population.

That said, a public data where you can re-identify your friends should not have been released in the first place.

But the famous have to deal with paparazzi! Peons are only exposed to insurance companies digging for pre-existing conditions, stalkers, violent exes, potential employers, ...

Because the average "famous" individual has far more personally identifiable data out for public digest than you or I, It's not about special treatment, just understanding the realities.

Sure, but the publicly available data is huge for lots of people. I don't see why you'd make an exemption for celebrities. If you can deanonymize people in sensitive data sets, don't release them. Saying "we'll protect the VIPs, the rest can go deal with the fallout of their employers looking at their personal health issues" isn't an option to me.