Lostspark,
“Why has space travel capability regressed for 50 years when every other technology has advanced?”
Multiple reasons:
1. Do a Web search for a chart of NASA’s annual budget over the years, and this alone should answer your question. The US threw in an unbelievable amount of money to get the Mercury and Apollo Programs stood up.
2. The Apollo technology was designed quickly (“before this decade is out…”), and safety was the top priority, not cost efficiency. A moon mission was prohibitively expensive and most of the equipment was designed to be used just once.
3. A big motivator for early US space efforts was a technological arms race with the Soviet Union. The Soviets got an early jump on the US in rocketry and getting satellites and people into space, but they never had an answer to the Apollo program.
4. Space programs since Apollo have primarily focused on low Earth orbit. We now have tons of satellites up there, providing GPS, weather data, communications, telescopes, etc. It’s a much bigger benefit (and military concern) for a smaller cost.
5. This wasn’t a factor in the cancellation of the Apollo program, but subsequent research has shown that interplanetary space travel has dangers that weren’t fully realized in the 1960s and 1970s: damaging collisions with tiny objects, solar radiation, health issues from staying in low gravity for long periods of time.