"a reduction in one healthy persons premium is an increase in...

"a reduction in one healthy persons premium is an increase in another's"

Whilst that would somewhat be true, I think the objective of the insurers is to influence their policy holders to remain in a healthier state, and therefore should translate to less payouts for varying medical services. Reducing outgoings means reducing premiums, and reducing premiums could mean an increased market share for the insurer against competition without this strategy in place.

I feel like this is exactly what is happening with WellteQ and their implementation of MyFiziq's tech in Toll. That being, they're creating a wellness App for employees to use to keep healthy. The more healthy their workers, the less days they take off.