Shortly after you will start see advertisements for treatments related to that condition.
So they are interested in your health condition as long as they can monetize it.
That’s they’re normal stuff. Search for anything you get adds for it. But the goal of big data is giving you those ads BEFORE you search. That’s the holy grail of target marketing. It’s not about giving you ads when you find out you’ve got illness X. It’s about planting the name of that drug in your head BEFORE you get the news from your doctor, so you already know what to ask for. And for THAT they need demographic trends.