I am always surprised to see it go down! What happens when a scant 21 million people want to hodl an average of 1 measly bitcoin each???
I don't think in todays date there are 21million bitcoin users and there aren't even 21 million bitcoin(there will never be those many bitcoins), so a simple answer- 21million people will never be able to hold 1BTC each, the situation is statistically incorrect.
Yeah that the point! 21 million people can ONLY WANT to hodl a whole bitcoin. It is after all the most secure and unchangeable ledger in the history!