Insurance companies mining as much data as possible to find reasons to deny claims. There is a very good chance that they will be (are already?) able to infer prohibited information to raise prices.
If they are concerned with racial issues (or similar), try pointing out how data analysis can hide institutional racism (or other biases) - even unintentionally - into the algorithms behind finance, criminal sentencing/parole, future employment opportunities, etc.
Even if none of that happens to apply, there are two big reasons they should care. First, the unknown. In the circus we call our current political environment, do they really want a future $POLITICAL_ENEMY to have a detailed map of who they are, what they do, what they like, where they move during the day and who was with them (COTRAVELER), and anything else modern machine learning techniques can find?
The final reason is... because it isn't always about them. Other people might be in worse situations and it's important to stand with them by normalizing sufficient privacy. In his essay[1] on why he wrote PGP, Philip Zimmermann said
>> "What if everyone believed that law-abiding citizens should use postcards for their mail? If a nonconformist tried to assert his privacy by using an envelope for his mail, it would draw suspicion. Perhaps the authorities would open his mail to see what he's hiding. Fortunately, we don't live in that kind of world, because everyone protects most of their mail with envelopes. So no one draws suspicion by asserting their privacy with an envelope. There's safety in numbers. Analogously, it would be nice if everyone routinely used encryption for all their email, innocent or not, so that no one drew suspicion by asserting their email privacy with encryption. Think of it as a form of solidarity."
This is similar to the concept of herd immunity[2] with vaccines. Vaccines are not 100% protection and some people cannot take them for various reasons. Those people still benefit from the general vaccine use producing fewer opportunities for infection. Similarly, when enough people protect their privacy, there is less incentive to abuse data thanks to lower profits and increased political costs.
[1] https://www.philzimmermann.com/EN/essays/WhyIWrotePGP.html
[2] https://en.wikipedia.org/wiki/Herd_immunity