Really it isn't the crewed spaceflight to the moon that's the point, it's the things we invent in order to send a crew to the moon. People talk a lot about velcro and tang, but the most significant outgrowth of the space program was the massive advancements in portable/durable computing that it pioneered.

In the case of a moon base, I think the most significant breakthrough still on the table is in-situ resource usage. The moon itself can hypothetically be turned into rocket fuel, greatly decreasing the cost to get there and come back, and mining the moon is a significant step to mining an asteroid.