Fitbit is not a medical R&D company. It's a fitness gadget vendor. Is all this data used for furthering medical research? If so, by whom? If not, why does Fitbit need it, and what does it do with it?

There is no medical R&D comapny that could run a test that fitbit runs as a sideshow to their business.

So either fitbit gathers this data or noone does. What will it do with the data? I hope it will anonimise it reasonably and puts it up on the internet for free but that's a bit unrealistic. I think it will pass the data to researchers, similar way other companies did in the past. That's beneficial in my book and I much prefer that scenario to the scenario where they just discard the data.

Personally I trust the recently completed[1] Apple/Stanford heart study with my health data a lot more. It's a company with a record of protecting personal data, and on the Stanford side was presumably approved by an IRB before they collected a single piece of data.

Granted it's not the same dataset as you'd get from a "Collect everything and figure out what to do with it later" approach, but I think it strikes a better balance.

For all we know, Fitbit's eventual plan is to sell their heart data to your insurance company so they can say "It looks like you have a higher than average resting heart rate and don't exercise much, we're going to double your premiums." Heck, maybe Fitbit isn't planning that, but they'll go out of business in 20 years and auction your heartrate history to someone else who does that. We have no idea.

[1] https://9to5mac.com/2018/09/01/apple-heart-study-survey/

Or you know, they pass it on to your insurer who can trivially deanonamize it...

Let's assume your worst case scenario. Data is sold directly to insurers.

Unhealthy people pay more (kinda fair don't you think?). Healthy pay less. Some have additional motivation to get healthier, because "screw the old me, I don't care about that looser... but if I move a little I can pay less now? Tell me more!"

Average society healthiness increases. Even worst scenario is great.

> Unhealthy people pay more (kinda fair don't you think?)

Depends. You can be unhealthy through no fault of your own (genetics, environment). From social utility POV, insurance is about pooling risk. Taking your scenario to the limit, if insurance company is able to compute an accurate risk factor for everyone and adjust premiums accordingly, then the risk pool evaporates. But then again, maybe health insurance shouldn't really be a private industry.

Insurance still works even if insurer knows exactly how probable is given outcome and how much exactly will it cost and adjusts the fee to that. People don't insure themselves because it's a good deal. They do it because they know they won't be able to survive financial burden of some rare event that most likely won't happen but they need to be sure that in the case it happens they'll be covered. And they are willling to pay for that.

Risk is still pooled because payouts come from fees of the people that didn't (and won't) experience costly events themselves.

More information just makes the business more just and less random for insurer.