Well... remember, some of the “money for Alfa” was work on a common architecture, some was rebuilding factories, and some was going to be spent in Italy regardless. Six billion is not as much money as you think in the auto industry and it's amazing they were able to do what they did on that money. While Alfa may not pan out, putting six million into trying to make Chrysler a global upscale brand would have been riskier and harder to manage, and he saw that in the world ahead, the only way to succeed — given competition from East Europe, China, Korea, etc — is to design and build more desirable, premium cars so that you're not going after low-price buyers alone.
Another point is that Alfa was purchased with the inherent promise that it would be revived when possible, just like Lancia. They tried to build up Lancia and it didn't work, so they are trying Alfa. They changed their approach when they discovered with the Quattroporte and Ghibli that you have to pretend your mainstream and upper cars are totally different.
SM saved the remains of Chrysler, refused to do a merger that would not be good for Chrysler and Fiat alike, did not try to do “a sale—any sale,” and brought thousands of jobs back to the US and Canada from Daimler's and Cerberus' outsourcing binge. Keep that in mind when you're looking at the Alfa Romeo expense. He put Fiat onto a serious diet, more severe than Chrysler or Dodge, when he took over. Chrysler lost one car, the 200. (The PT was already moribund.) Chrysler has often sold just one or two cars with different trims and nameplates, too, historically. It proliferated in the 1980s but that weakened the brand.
He had some extremely tough choices. Alfa is in some ways a test-bed for Dodge now, according to some of the insiders here — they pioneer (expensive) and Dodge adopts the ideas that work and implements them their own way. That means technology moves faster for Dodge. In the past, they could try new things on Imperial...
Moving Chrysler up wasn't working. Cerberus tried it, FCA kinda tried it, to some degree Chrysler Corp tried it with the LHS and 300M. The Concorde sold like gangbusters but LHS and 300M really didn't, not without heavy discounting. In the later days DCX and then Cerberus tried “Chrysler starts where Dodge leaves off.” It didn't work too well. They could either revive Imperial, at that point, or revive Alfa, which had never really left. I don't have any great love for the Alfa brand, but I suspect it made more sense. Whether it works or not, is hard to tell.
Lexus worked very very well because Mercedes and Cadillac and Lincoln had all dropped the ball, and if you wanted a good, very quiet, very comfortable, economical, and above all reliable car, Lexus was the only way to go. Infiniti tried doing the sporty thing like Alfa is, and they failed. Acura, too, tried the sporty route, and they also failed. Maserati, you may have noticed, opted for the traditional American interpretation of luxury, which is the grand tourer, — good handling, big engine, lots of space and comfort — and while they didn't set the world afire, they made gobs of money and doubled their sales pretty easily.
Perhaps the new Alfa/Maserati media reach-out will change their fortunes? Or perhaps they will wow us with an electric car later.