"No ground in reality" according to you. History is full of the success and failures of people trying to achieve such pie in the sky ideals. While past success is not a true indication of future success, Musk has a history of delivering.

Your argument comes across as "There are unsolved problems, and it's expensive, so don't try". Attitudes like that don't drive human progress. Society was not built on "it's hard, so don't try". I'm kind of surprised that this attitude has to be argued against on Hacker News, of all places.