This is a slightly wrong question, I think, since the answer is "because they can". They are a business and will take every opportunity at monetisation. They really nailed the marketing of virtual collectible toys.But it also begs the question, why? Why do they still need so much money? What is their actual burn rate if they have to keep doing this? Why are they doing more concept ships that just add more time to development rather than releasing ships that backers already paid for, in some cases, almost a decade ago?
Besides, that new office in Frankfurt and a hundred of planet designers at Turbulent are not going to come free.