Also one or a few people turning it off doesn't matter much. The tech giants still get their demographic statistics from the ones who haven't (which is the larger percentage of the population). You could be spending money on things based on targeted ads for your demographic.
In other words, you are creeped out about wondering what they could do with your personal data if you turn it on. But you should be even more creeped out about how your daily decisions are already influenced by them using others data