99% of the population doesn't wear fitness bands and doesn't need one. Most those that do have a fitness band don't wear it at all times.
With SOLI, everyone that is in the neighborhood of a SOLI-enabled device, that is a mobile phone, or, soon, a SpyNEST heating control, or SpyTV, or SpyFridge, or a SpyCar, will have their heartbeats monitored 24/7.
Changing the world from monitoring 1% of the population to monitoring 99% of the population. That's the story of Google/SiliconValley, from NielsenRatings-to-GoogleAnalytics, all the way to Fitbit-to-SOLI.
Isn't it too late for that? Every $15 heart rate monitoring fitness band is already doing that, along with Wear OS watches.