Canceling a mission to Mars would not put one biscuit in the mouth of one homeless person.
Some people reason like children.
OP also fails to understand that many high tech good paying jobs are created through all the various contractors connected to any project.
That's a lot of biscuits folks can provide for themselves.
Each step we take brings us closer to being a true space faring species. Despite the naysayers, I believe it is an inevitable that humans will eventually occupy Mars, and the several moons of the gas giants known to contain water. Eventually mining the asteroid belt for resources.
They lack vision and imagination, but can never stop the dreamers and doers and the driven instinct within many that screams...
"I wonder what's over there?"
We haven't got this far on the ideology of Can't be done.