I don’t think anyone has suggested the space program is a waste. The issue is the continuance of the manned space program in its present form of sending men into the same low earth orbits, filing their time with high school science experiments, literally in many cases.
The idea of manned space flight powered by chemical fuel is just silly any longer. Were NASA able to develop technology, presumably nuclear technology, that allows much greater power generation per pound of payload, the entire equation changes. I am not seeing much of an effort in this direction, presumably because they simply don’t know how to do it. The sail propulsion technology is the only interesting exception of which I am aware.
I would be interested to see a description of what we have learned or developed as a result of the ISS. Like Skylab, I have expected it to be a total loss since the inception of the project.
On the other hand, if we can drop a nuclear reactor on the moon or Mars and develop robots to do infrastructure construction prior to human arrival, my opinion would change dramatically.