Fun is important because directing and motivating teams of humans is a difficult skill -- especially when you want to do things where the path forward is at all nebulous, like materials and design research.
I guess I just cannot share in the purpose of the team making this car go +300 mph. We already have the Thrust SSC (1228 km/h / 763 mph). So what does this prove? That if you want to take corners and need to see what happens behind you, you won't get to go that fast? Why not productionize the Thrust SSC then?
Max speed (to me) is just a senseless metric. It's a bit like clock speed of a CPU. Interesting metric, but only in relationship to other factors.