Its not sour grapes. When Neil Armstrong went to the moon it was for all Americans and all of Humanity. During the space shuttle missions there was a public effort to try to select a broad representation of cultures, backgrounds, educations, nationalities etc to be astronauts.
However, if the only ultra rich get to go, which it sounds like the case since that would be the only way to fund a private mission, why should everyone left be ok with it? Why should the richest people in the world, most who have had a incredibly large role in environmentally destroying the ONLY planet all of humanity can live on, just leave everyone else to clean up the mess? It would be the ultimate FU to the rest of the 99.9% of humanity.
http://www.theverge.com/2015/11/24/9792854/neil-degrasse-tys...