To compare the two is an effort in futility. Both are laudable but incomparable. To finish the Ironman is an admirable achievement, no doubt. The dedication, persistence and determination required is impressive. However, to quote my dad, who was a Navy Seal, pain “is a state of mind.” Competing in an endurance sport requires conditioning, strategy (if you actually want to compete) and the ability to take yourself to a happy place and turn your pain into pleasure. With enough practice, the right diet and the ability to re-sculpt your body, it is doable.
The CFA requires some of the same characteristics (think dedication, willpower) but otherwise is a completely independent event. Sure, anyone can do it according to this board. But, the stats prove otherwise (womb to tomb). With pursuing the Charter, unlike competing in a triathlon, your progress is difficult to quantify. With endurance training, you know when you are making better times, looking and feeling more fit, the lactic acid buildups are dissipating etc. In pursuit of the CFA designation you tangentially feel as though you are making progress but you have no clue until you actually write the exams on little to no sleep do you understand your true level of mental conditioning.
Therefore, with endurance training the progress can be plotted, seen and felt. In pursuing the Charter, your “training” may be more of a mirage, not fully understood until the day of reckoning. FWIW, I agree wholeheartedly with Black Swan. Focus your efforts on completing what you started before becoming involved in another task that will wear on you both mentally and physically.