Comment by AIPedant

It would also cost more power to construct than humanity is currently capable of generating in 10,000 years, so I am not sure what your point is.

Presumably a 5% functional Dyson sphere would be a corrupt boondoggle in the same way as a power plant which is down for maintenance 95% of the year, but the financial calculation would use much larger numerators and denominators than we are used to.