Many of those accounts are custodians that hold bitcoin for a large number of people.

But yes, just like with other forms of wealth, bitcoin wealth is concentrated. Over time, these bitcoins will be spent because people eventually die and want to enjoy their assets before death.

It’s like the Vanderbilts and Astors from the 1800s. They were some of the richest families in the world but now the majority of their wealth is gone, dissipated by the generations over the years.