Could AI Reach a Stage Where it Makes Decisions For Us?

Technology has already reached a stage where it is collecting a vast amount of information from us all the time. As a case in point, just look at fitness wearables. The Fitbit Charge 3 knows your heart rate at all times, your sleep patterns, and when you're in fat burn or peak zones. This data helps users make the most of their workouts, and they appreciate it. But how long before hardware like this starts tracking other bodily functions such as hormone and brainwaves? By tracking our reactions to different stimuli, technology may soon know what we want before we do.