> The "self-sustaining city on Mars" bit is a pipedream, and not something we should spend serious amounts of money on in the 21st century.
Compared to the roughly $100,000 billion/year combined GDP of all nations, the $8 billion/year [0] Musk is trying to make the Mars colony cost is a rounding error, not “serious” money.
[0] 1e6 people at $200,000/person, divided by 25 years for even the most optimistic timeline