Strava heatmap can be used to locate military bases
In some cases where the data is sparse, you can find where individual people live, because the trails sometimes lead back to a starting point. Like this person who runs around the park regularly. Of course you could also just follow them IRL if you were there, so I'm not sure this is a big deal.https://labs.strava.com/heatmap/#14.20/100.20693/40.99133/ho...