"Because the USSR is doing it" was an equally bad reason.
Once that was proved, and the technology to deliver long range nuclear weapons implemented, the motivation to push this stuff at all costs dropped.
Put another way: back then it was science in the service of warfare with an effectively unlimited budget. Now it's mostly just the science.
The moon mission had only one goal: to save the face after the US has lost all meaningful milestones to the Soviet Union and to "win" the space race by moving the goalpost. I am quite confident, that if the Soviets has managed to land on the Moon first, the goalpost would've been landing on Mars.
With rapidly dropping launch costs there's valid industrial applications in orbit and quite a few startups working on building things in LEO and bringing them back down. Microgravity is incredibly valuable in manufacturing, the Brits worked that out in the 1700's with shot towers. Same with ultra low temps and vacuum conditions.
No way that is true.