I'd say Star Citizen is more of a cautionary tale about putting blind faith in someone just because of previous results. Chris Roberts has previously delivered, but in all cases where he has it's been where he's been under someone else's direction.

Without someone to constrain him he tends to constantly expand the scope of his projects. If people knew about his involvement in the debacle that was Starlancer/Freelancer then they would've seen this coming.

So no, it's not a matter of being 'too ambitious'. It's a matter of shifting the goalposts and expanding the scope of your project to the point that it never actually ships. When he had someone to stop him from doing that he delivered. Without that, he just keeps soaking up money as long as people will enable that behavior.