What real, actual risks which I didn't already know about have been shown in this thread?
The point is that while you can use DNA to identify people in most cases, sufficiently motivated adversaries have more effective, cheaper, lower-technology approaches that they will use first.
Like with many things, the issue is the aggregation of data on many individuals (a database), and easy accessibility of your individual data on request (discoverability and processing).
Me shouting my sensitive private details in a crowded bar is entirely different from putting them on my webpage. There's even a difference between writing them down on a napkin or shouting them out.
