Musk has done so many smart things, like the Mega Battery deployed in Australia and many battery techniques. If only he could be persuaded to direct his Million $$$ at reducing plastic consumption, clearing plastic from the oceans and providing employment opportunities for products and schemes that will help a WIDE section of the globe.
All the money spent on Mars and this hypersonic dream is wasted. They will only benefit a minority of humans. He could really turn himself into Mr Nice Guy, but that might involve some changes ...