Well experiments have been done relevant to cancer research and treatment, heart disease, virulence of microbes like salmonella, basic physics of colloids and crystals, improving resistance of materials to space weathering.... but no, if you want me to point to something and say 'this is worth 100 billion dollars' and give you a breakdown of how and why that is true I can't do that. To do that I'd need a time machine to go forward 100 years, put all their discoveries and what they've contributed to and led to into their proper historical context, and then make a judgement on them.
Its a research lab, not a business. All you can demand of it is that it does as much research as possible, as intelligently as possible, and for as long as possible.
In space PR and Politics are as important as engineering and science. And no-one can hear you screaming about it.
"There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy."
Exploring other worlds with people is a great idea, but look at what has happened since the end of Apollo: How much could unmanned exploration (and astronomy) have discovered with all that money blown on paper rockets?