Your claim is that if they are independently wealthy, OR are willing to forego food and housing, COBRA will save them from unexpected healthcare costs.
I did not claim it would save from unexpected costs. The full premium is an unexpected cost. I claimed COBRA is more affordable than out-of-pocket healthcare if you are in the middle of an expensive treatment at the moment you lose employer coverage.
Jumping onto ACA via unemployment exemption or Medicaid could require a transfer to a different doctor, etc. in the middle of treatment.