Because it's impossible. You don't know how a technology can be used in other applications unless it already exists. That's effectively like saying, "instead of wasting money researching how cancer works, why don't we research cures and drugs?" The answer being, of course, you have no idea where to start without research.
You might not be personally interested in the scientific papers resulting from space probes, which is totally okay. But the reason why NASA is such a fantastic investment is because they work on problems that humanity has never attempted to solve before, and in the process they create technologies with diverse usages outside of space technology. But that doesn't change the fact that the sole, ultimate reason why they made that tech to begin with is because they wanted to send a probe to research a planet. That's why you can't separate space research from NASA spinoffs. The esoteric and ambitious nature of the problems they solve is the reason they're so innovative. Does that make sense?
To put this in perspective: "As of 2016, there were over 1,920 Spinoff products in the database dating back to 1976."
- WikipediaEvery single one of those technologies are UNIQUE.
The entirety of the NASA budget since the 1960's summed up is less than the 850 billion dollar bank bailout in 2008.
Space travel has already revolutionised our lives weather you like it or not, even if you don't notice and it is distinctly cheaper than waging a war or any other kind of technological boom. I actually can't believe he compared it with WW2 in any way shape or form, since space travel has excelled showing the good of mankind. Almost all space ventures are international collaborations, or if I quote JFK:
"There is no strife, no prejudice, no national conflict in outer space as yet. Its hazards are hostile to us all. Its conquest deserves the best of all mankind, and its opportunity for peaceful cooperation may never come again."