According to analysts at cryptocurrency company Chainalysis, of the existing 18.5 million BTC, about 20% lie in lost or otherwise blocked wallets. In total, this is about $140 billion.
Is this amount reported to anywhere or people are speculation only? I guess there are a lot of early bitcoiners have lost their BTC in such a proceed; either forget the encrypted password or have spoiled their drive, hardware etc. There was another article where I have read it was 1 million or 10 million.