This loan is their Hail Mary pass.
They need the cash to get them to Gamescon and 3.0. The future of CIG is riding on how much they pull in during those events.
And then what? Remember, as people have noted repeatedly, they do not have a game. You cannot walk into Best Buy, or log onto Steam, and buy Star Citizen. It is not released.
Ergo, they have no cash flow from people purchasing. This isn't complex, it's business 101.
What they have are people who are buying 'futures', effectively paying for future benefits in the game. This isn't new -- heck, you could argue that Patreon and crowdfunding work off it -- but I doubt they're bringing in enough cash as time goes on and the development cycle gets longer and longer. People are reading the Doc's writings, and OSC's writings, and are starting to ask uncomfortable questions.