My theory is scope creep. These guys have done a good job of convincing people that they can live the ultimate space exploration fantasy that's been talked about since the 80s.
It's the ultimate simulation. We know very little about space and even fiction (ex. star wars) seems to generate even more demand.
As people got excited and started throwing money at them, so did the scope obviously. I love Star Citizen's attention to detail but it's suffice to say that they've hit people's patience.