Side effects of these projects, even if they fail, may be massively valuable. Sometimes solving problem X that isn't a big concern for society will solve problem Y down the track. History of maths is littered with things that were useless when they where first invented, such as imaginary numbers.

I'm still not arguing that and I'm as excited as everyone else when someone comes with a bold idea as this, still, you can't gouge how well the money will be spent and downplaying risks and alternatives of undertaking a multi decade project because we are in the heat of the moment is not wise. Science justice warriors should take a deep breath before pointing fingers imo. We are inherently in a box and I doubt anyone can imagine what technology will look like in 10 years, let alone 40.