And yet, banks and financial institutions are vastly preferring blockchains that have been uniquely developed for their needs. There's very little appeal in simply accepting the transaction costs and times in bitcoin when you can spin up a version with whatever spec and interoperability you desire.

If by 'return of capital' you mean a propensity for an asset to retain its value, bitcoin is utterly inappropriate. Even gold is far too volatile and is only rationalised on those grounds against (very) long tail risk.