But surely, celebrities have personal telephone numbers and e-mail addresses too? Direct points of contact reserved for their relatives and closest friends?
Of course they do.
I'm assuming that the average person has anywhere between 20 to over a hundred personal contacts (i.e. relatives and friends). Celebrities are no exception, are they? But how can they be sure that ALL of these 20-100+ contacts can be trusted to keep the information secret? And if only ONE of these contacts leaks out the information, it would spread like wildfire, wouldn't it?
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Finally, I might be a cynic, but I believe that even when you're given a group of only 30 people, the chance that EVERY ONE of these 30 can be entrusted to a secret is very, very, very minimal, bordering on nil.