The other MCOs all had net income less than $8B (CVS/Elevance/Cigna/Humana/etc).
There is no way a business earned a profit of $18B just from Medicare and it not being visible on their net income figures.
That is not to say Medicare Advantage is good for most customers (the common advice is to stay away from it), but fantastical numbers don’t help arguments.
But even supposing that the business earns $18B from Medicare Advantage after all is said and done, it doesn’t pass the smell test because at that level of profit, these businesses should shut everything else down and just do Medicare Advantage.
And for all of that, you’re stuck paying at least 20% of everything, on top of separate deductibles for each part and no out of pocket caps at all (meaning Medicare isn’t even an ACA compliant health care plan). Part C simplifies this for so many people by rolling all of Part B, Part D and usually vision and dental into a single premium and puts out of pocket caps on the amount of money you might need to shell out. Is it any wonder people keep choosing Part C even if it means their providers have to fight the insurance more?