We went there. It was expensive. We learnt a lot. But also that there isn't much you can do with the moon. Sure we could put a base there or build a hotel or something but it isn't rich in resources and it isn't exactly beautifully scenic. Instead of sending more people back, we built probes that could be sent there to take photos and gather information without the need for a human onboard at a fraction of the cost and risk. Instead of sending these just to to the moon we sent them to every planet within reach and even moons of some of the larger planets. We then developed robots and put them on mars to take surface samples and gather more information. Now efforts have shifted to mars, because it does have resources, may once have had life, albeit very basic single-cell.