Unfortunately with Trump being there, this shall not be the greatest launch, for he may plan to use this for his own propaganda campaign.
What then, in my view were the greatest launches? Indeed, when the cosmonaut Yuri Gagarin was launched and Apollo 11 went up, that was a monumentous achievement for mankind.
Unlike the Apollo and space shuttle missions and all who have went before, there is little scientific reason for this launch. It is space politics; all that money could have been used to build homes instead, to improve the general wellbeing of Americans, instead of enriching and entertaining the billionnaire oligarchs' interests. But that is my own view, I s'pose.
Had Americans' wellbeing been improved greatly, the FPTP system abolished for proportional representation, and there been no billionnaires and media oligopolies, no conflict of interests, no wars the US was waging... the US might have faced a much more golden age of spacefaring.