Cloud Imperium is not a tiny company. I believe it has about 1000 employees at this point, which means that the 600m has mostly gone to keeping the company going.
Chis Roberts is burning the cash rather than pocketing it. He loves his feature creep, and which forces devs to redo work. They've thrown most of the game out and coded it from almost scratch twice?
Every single Chris Roberts project has been like this. Development hell with new shit being added and no deadline in sight.