I can't recall what I did the first time I ran Core years ago, but the current dialog box has the "Use the default..." radio button pre-selected, the "Use a custom data directory..." button not selected, and "/Users/[me]/Library/Application Support/Bitcoin" in the field in which a custom directory can be specified. (Entry in that field is disabled unless the custom directory button is clicked.) That is in fact where the data is, and indeed the dialog box says under that field, "Directory already exists. Add /name if you intend to create a new directory here." Then outdented underneath that, "When you click OK, Bitcoin Core will begin to download and process the full Bitcoin block chain..." Is the latter statement inaccurate in my case?