You do not understand the analogy.  Everyone needs water to live, but too much will kill.  Too much CO2 will kill also.  Too much O2 will as well.  We need H2O to survive just as much as Oxygen.  Go without water and after a few days you won't need Oxygen because you will be dead.  I'm not aware humans need to breathe CO2 at all.  Somewhat tangentially, although it does illustrate the profound depth of your ignorance, a minute without oxygen will not result in a loss of consciousness for most people.  Many can hold their breaths much longer.  A lack of oxygen will not produce death within two minutes.  If so, CPR would almost always be impossible.  Brain damage will occur after the seven minute mark.  A high school level knowledge of biology should provide this information.