Tech companies when they speak to VCs: look at all the creepy things we can infer with ooodles of aggregated data and AI to maximize targeted ad revenue, we're worth 50x what an equivalent non-tech company in our sector is valued, because of all the things we can do with all that data from all those people together
Tech companies when they speak to their customers: oh you're so silly to even ask about privacy, what possible utility could there be in that single isolated variable?
(Note 1:"Dr. Bootlicker, the defendant wants the court to believe that she calmly placed herself between the agent and the minor he was trying to apprehend, and asserts that the agent's claim, that the defendant's actions constitute assault, is, in her words, 'ridiculous'. But am I correct in understanding that you view minutes 8 and 9 of the biometric data submitted to the court as characteristic of significant physical exertion that might be similar to that undergone by an assailant while commiting an assault?")
Bad health? Raise the insurance premiums? Or anything more evil I can't think of.
edit: grammar
A capitalist, or as in this case, fascist, state might figure out all sorts of interesting things from mass surveillance, such as who might be disloyal, who is eligible for eugenic culling, who might be fun to deport, and who is vulnerable to sticks or carrots or both and could do something for the state that the state does not want to do directly.
What could they possibly do from this single variable???
It's not in isolation. It's in aggregation. So you end up with
"Mr. Smith's heart rate goes off the charts for six minutes every time his phone visits this apartment building in the middle of the night and is within radio range of Ms. Jones' phone."
For example, A is known to have been an associate of B. B died violently at a certain time and date. Phone data put both of them in the same general area around that time. A seems evasive and won't talk. But A's biometric data reveals intense physical activity around the time of B's death...
Other suggestions in this thread like algorithmically making things worse for people in general are predicated on continual availability for a whole deanonymized population.
"Mr Smith has been running again, we better bring him in for questioning!"