Didn't their plans become more ambitious as they continued to raise more money, which could explain the delays.
I think the developers have good intentions, at the very least. A "scam" implies that they are manipulating people to get their money, and I'm not sure if that's the case. I know very little of the project, so this is all just speculation.
Well, the people who quit said Robert's won't make up his mind on things. Or when he does he changes so things have to be redone. There's one of two things going on. He's either an extreme perfectionist and wants everything a certain way. Of course, if that were the case, they could still put out the product, even if it wasn't 100% finished, years ago and update it regularly, a la No Man's Sky.
Or he's using perfectionism as an excuse to keep this money train going, while having to put out much. Seems he was able to make up his mind on buying a $5M home last year. And on giving his family and friends high paying jobs that he refuses to disclose how much they make.