Scotty, while that's true that the others could have done their side project during this hiatus that Portnoy wanted, but there is no guarantee that they would have made nearly the money that they did with DT, or really much money at all. If I am Rudess, Myung, LaBrie, or Petrucci, that is too big of a risk to take; no way do I agree to it.
I think it goes without saying that they wouldn't make as much money as they would have in comparison to using that time for DT. But give the guys some credit for how they use/spend their money. JP is business savvy, and you can be sure that at least he (and I would expect by extension, the others) all use their money wisely so that they can live a very comfortable life, but still keep a decent amount of money in the bank. They aren't a bunch of idiot rock stars who blow all their money on drugs, exotic cars, etc and then have to file for bankruptcy a couple years later.
Additionally, one thing that you and others may not realize is that the money that those guys make from albums, tours, merch, etc. goes into a big pool of money from which they receive regular payments, as opposed to getting everything in one lump sum. That way, the cash lasts longer and it can afford them to take periods of time off from recording and touring. Exactly how long that money would last without them replenishing with a new DT album/tour is unknown, but I'm sure that it would have been enough for them to live off of or else MP would not have brought up the idea in the first place. MP may come off as demanding at times, but the man is not a fool and wouldn't have pushed for something if he didn't think it was feasible.
And if it was about making sure that they were still financially secure, the other guys would've made some sort of mention about it after he split. But the only thing that was ever expressed by them is that they didn't agree that they needed a break from each other and to a degree, they expressed concern over losing the momentum they had been building over the years, especially since they signed with Roadrunner.
To me, the saddest thing about Portnoy's post-departure career is that he wasted so much time in Adrenaline Mob. Like you said, one of his biggest strengths is putting together, or becoming a part of, great projects, but that was one huge swing and miss.
I completely agree that he failed with AM, but he must've felt strongly enough about it to pursue it to the degree that he did, come hell or high water, and for that I give him credit.
MP's choices were certainly all made with many considerations, artistic, creative and financial. But IMO I can't help but believe the predominant driving force in his plans was the A7X gig. Mike is a rock star, but A7X provided a chance to be a HUGE rock star on a scale the prog world will never take him. And with that, the money, fame, adulation and lifestyle most 12 year olds dream of when they pick up a pair of sticks or hang a guitar around their neck. I can't blame him for this but if I am right I think it was a gamble that has proven to have not gone his way.
There's no doubt in my mind that he had his sights set on A7X - even the guys in that band implied as much when they explained how he told them that he had quit DT, so now he could spend more time with them. And yes, it was a gamble that he lost on.
Having said that, I am personally happy for the band and the direction and attitude that seems to have focused them is a slightly different direction.
Agreed. While I still do feel that there is something missing from the last 2 DT albums, in terms of the general music direction they're going in, I'm happy. I didn't necessarily mind some of the more metal/heavy directions that MP was pushing the band in (loved the super fast double bass in ANtR) but I hated the pseudo-cookie monster vocals that he wanted as a part of DT's scope of music, as well as his attempt at blast beats which didn't fit in ANtR at all.