Then why did they do an about face in strategy? Because the future was so bright they couldn't stand to look into it?
An initiative like the Starcruiser doesn't fall neatly into one single category for Disney. It's not strictly a matter of "If it makes money, it's a success, if it doesn't make money, it's a failure." It's more complex than that.
PR: In my opinion, Disney bungled the initial marketing for the Starcruiser: cheesy videos, poor explanation of the concept, super-high price. But Disney has been able to point to this innovation to show that they're still on the cutting edge (and maybe falling off of it..) of family entertainment. This was actually in doubt after some of the successes of the competition.
R&D: Disney spends loads of money developing and testing products and experiences. Robots (like the stuntronic used in Avengers Campus at DCA or the few droids they've recently tested in SW:GE), food, shows, systems, software, traffic control, etc. Most of the time, Disney doesn't see a return on R&D expenses until they're converted to products or services.
The Starcruiser had immense R&D value (see the article recently shared by
@wdwmagic above that talked about the survey Disney sent to Starcruiser guests). The Starcruiser had the highest guest satisfaction ratings of anything Disney's ever done!
They were able to build something that pleased vast majority of paying customers! Now, they've got to figure out what it was about the experience that made it work well and adjust so it'll make money without losing what people loved about it. This is R&D, and while it was expensive, some of the costs were offset by paying customers.
Was the Starcruiser a success? It depends. I think we can all agree that commercially, it was not. But in other ways, it is/was very a very valuable project for Disney and a rare success in pleasing the majority of those who experienced it.