When your pledge for a concept ship, you are pledging firstly that the money will be spent on the game and that at some point some sort of similar to the concept ship will at some point in the future be put in the game. At that point you can look it up and fly it. So for example the reclaimer was a concept ship I think in 2014 and is supposed to be available later this year (maybe next update maybe not, its star citizen nothing is on time including the presentations).
What you should have is a freelancer (you know the horrible view screen ugly as hell ship) to use instead. This way no matter how bad they make the Vulcan you will be pleased when it comes out because you no longer have a freelancer.