The fact that you managed to get people to go along voluntarily with something harmful to them by presenting it as something benign does not make your actions ultimately benign.
And yes, there comes a point where simple observation crosses the line. This is generally recognized by society. If I take a picture on the street and a particular person happens to be in it, that is generally OK. Most people wouldn't look askance at that. If I take a picture of the same person through their bedroom window, I'm liable to be arrested and labeled a creep. The specifics of information-gathering matter very much to how OK it is in terms of social acceptance.
And yes, there comes a point where simple observation crosses the line. This is generally recognized by society. If I take a picture on the street and a particular person happens to be in it, that is generally OK. Most people wouldn't look askance at that. If I take a picture of the same person through their bedroom window, I'm liable to be arrested and labeled a creep. The specifics of information-gathering matter very much to how OK it is in terms of social acceptance.