I’d argue that since January 2009 about 50% of the ~17M coins minted to-date are lost. But the realization that this number will asymptotically approach 100% of all coins is a bit striking.
The reasoning is simple - maintaining control of your coins is surprisingly difficult. The harder you try to secure them from theft, the more likely an accident will wipe them away. The more redundancy you keep to protect from losing them, the more they are exposed to theft. And as time goes on, the random noise of life conspires to blot your coins out of existence. And once they’re lost, there is simply no recovery.
The supply of Bitcoin is not asymptotically approaching 21M. The supply is approaching zero.