I don’t know that taxpayers “thought” about the cost of the space program and decided to give up on it. It could be true, but that’s not how I’ve seen politics work. I think it more had to do with the fact that we beat the USSR and the USSR stopped competing. There weren’t any really major milestones to be had after the Moon, either. Sputnik proved to Americans that the Soviets could fire a missile from Russia and hit the US, and we didn’t have a similar capability. Nothing has been quite that scary since.

I think it’s premature to claim SpaceX will make it to Mars without deaths. They’ve only done two manned space flights to LEO at this point. While it does appear to be easier, cheaper, and safer to send people to space, sending people to Mars has never done before. It is going to be extremely dangerous.