It's still a very different scenario to specifically acquire a single targeted person's DNA which they left lying around, than to collect a massive database of

It's still a very different scenario to specifically acquire a single targeted person's DNA which they left lying around, than to collect a massive database of millions of people's DNA that you can use to make all sorts of queries for whatever purpose you wish. E.g. insurance companies wouldn't go through the trouble of following around their customers to catch their DNA, but they certainly would like to have that database which can predict their future illnesses.