The population who ditches them might also be skewed towards developers, which might mean that less people are hacking on the Fitbit SDK which could hurt their ecosystem. Apple has tried to court developers for this reason. Losing a piece of that market might be more hurtful to a company than losing a similar absolute number of the general population.

My mother had a fitbit and has gotten rid of it. She didn't mention it on social media because she dislikes social media companies and chooses to avoid them, which seems related to her decision to avoid Google-owned fitbit.

So there is a selection bias in play. Many of the people who dislike google enough to get rid of their fitbit quite possibly also dislike social media and won't be reflected in statistics gleaned from social media.