Revealing mistake: When Bond knocks Blofeld unconscious with a lamp in the fight at the start of the film, look carefully and you can see that Blofeld is already knocked out before the lamp comes into contact with his head.
Revealing mistake: When Bond hoists Mr. Wint overboard with the bomb tied to his coat-tails, Mr. Wint is not Bruce Glover but a stunt double.
Answer: If you mean by hiding - why is he never seen normally - then it's because he is a recluse and doesn't like to be seen in public (like Howard Hughes was). If you mean by hiding - why was he not seen during the movie - then it's because he was being held captive by Blofeld and his minions. Spectre didn't want him out and about ruining their plans.
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