@margusl that is more or less the main topic - trust.
I trust Strava approx as much as Facebook, Apple, Google and Windows, and although I absolutely understand that I have to disseminate my (personal) data in order to see nice curves, maps, etc, and am absolutely willing to do it (and of course already doing it), I at least try to limit the number of services which are receiving the data directly from me. And, of course, try to avoid the “worst ones” (following my own judgement and not always the general terms and conditions with the nicest wording).