>>>Thing is, if it actually is profitable, there is no reason for them to ever stop, as Mlsoft is waiting for them to do.<<<
One of the main reasons it works so well is that it is an orchestrated effort by the Fed where everyone wins (the players that is- not us little guys). The PPT main goal is to avoid panic. I think that they feel that they have had some level of success even when the the market goes down in orderly fashion. If you read some of the white papers after 1987 you will see that there was great concern about another 1987 type crash. Much was written on how to avoid it. It wasn't so much about the markets going down but more on how they went down. Of cousre now they also have to be concerned about the world economy. I'm sure the thinking is, "if we can only keep this together until the next recovery".
The reason they may stop is that they could get to a point where their intervention may become counter productive. Once the Fed as the "conductor" drops out, the others are left to their own devices. This would mean more risk to them. That may give them pause or reasons to curtail their operations. Like Mlsoft, I think their must be some limit to how much the Fed can continue to intervene. We just don't know where that limit is.
Joe