For what it is worth, his costs look outrageously low to me. We don't even know what we don't know on building manned interplanetary reusable spacecraft and making indefinite term extra-planetary habitats.

Musk's promises that they'll travel in comfort sounds too close to what the Jamestown colony residents were promised. Life on Mars is going to be a hardscrabble existence where you have to solve problems that you don't have on Earth. Probably a mostly subterranean existence.

Musk's video seemed to imply that people would terraform Mars, but we aren't even close to attempting that yet. We can't even keep the atmosphere of Earth in balance. Elon Musk's biggest problem may be that he was born 100 years too early.