re: All things considered, why is the Federal government involved at all in health insurance ?

Yes. It is most definitely ideological. Sure, lots of entities use it to line their pockets as well, but the Democrat Party is mostly socialist in its ideology now. They would have gone for a single payer system to start with if they thought they could have. Knowing that wouldn't have initially gone over well, they just pushed though some sort of nationalized form with the intent of eventually getting single payer once folks had become dependent on it.