To be fair, the question would be for hospital systems and not physicians directly. It's one I don't know the answer to.
But the idea is ludicrous. To suppose that it's happening means falsifying medical records which are seen by dozens of people who would know better. And since nearly every chart is electronic, there really is no way to do that without modification being immediately apparent to anyone who looked at the record. So basically the only way would be to have every doctor, nurse, tech, respiratory therapist, etc. etc. wholesale in on the conspiracy. The idea that you could pull it off for one patient seems highly implausible to me, much less on any scale to matter for the argument at stake. And, as you point out, physicians would not get any of the financial take under their reimbursement model. Pretty much everyone else would be in the same boat. So you'd have to pay off quite a lot of people to even try to get away with it. I think whatever this possibly not even real increased revenue would be, you'd be very far in the red trying to profit by paying employees to commit fraud. I was hoping
@Batmeat would have replied with some bounds on his assertion, also, because basic math could likely easily defeat it. Unless of course, they are making up the existence of patients altogether and finding someone to pay for said imaginary patient? Things get really funny if you try to work out how you could actually succeed in this conspiracy.
Another way of looking at this: medical fraud is real, and if you wanted to do it, there are far easier ways to succeed.