To be fair
The best way to convince those who don't believe in the importance of the space program, is to google on all kinds of references proving your point and show them to the detractors.
If they are ready for the arguments, it's fine; if they ignore them, it's not our fault.
It is indeed unfair to learn many believe NASA spends more than 10% of the federal budget, and can't make the difference between a high figure which is published and a much higher figure which is hardly ever published.