How much capital do I need to retire comfortably on
For a lot of people, it's more capital than they have access to.
Many people approach retirement with little or no capital. Many others approach retirement with no debt-free housing. Sadly, New Zealand's retirement model is based on debt-free home ownership at retirement.
This is already causing problems as the working poor morph into the retired poor. Changes in population structure will only emphasize this.
The model is broken, but politically it's a live-rail issue which nobody - irrespective of party - has any intention of touching.