Humanity has sent people to the moon and brought them back safe. This is a hell of an achievement, but it would pale in comparison to sending them to the moon and keeping them there. The trouble is, we're not using technology that can do that. We've gotten locked in by the related phenomena of local maxima and path dependence.
Local maximum is what you have when you're on a hilly landscape. There are lots of peaks, some higher, some lower. Any given point from which every direction is downhill is a local maximum, but there's only one global maximum in the given area.
Path dependence is what happens when you start using and developing a technology. We've done astounding things with the internal combustion engine; Otto and Diesel would barely recognise the marvels we have now, despite their using the same thermodynamic cycles and the same basic principles of operation. The trouble is, we're now at a point where the internal combustion engine is holding our technological development back; we could do great things, but we're tied emotionally and technologically to this bulky, heavy, smelly, inefficient contraption. Worse, our reliance on it has slowed development of other motors; modern electric motors are not far removed from the original designs by Tesla. We got locked into the path of improving the internal combustion engine, which path has now peaked; and at a local maximum.
The same thing has happened with space travel. When we first got interested in it, rockets were the easiest thing to try; and we got very, very good at rockets. The trouble is, rockets have abysmal payloads for the long haul, and they have vast amounts of waste in their construction; most of the Saturn V that took men to the moon was simply there to get them through the atmosphere. It took an incredibly heavy lift capacity to get three men to lunar orbit. We simply can't send up enough to make a moonbase viable that way. Rockets have reached their peak, and every other technology will require a step back down; something we're unwilling to take.
So we don't have a moonbase because we're an annoying combination of stubborn and idle. We don't want to take the time to develop technologies that can go further than rockets, because they won't be able to go further than rockets immediately we introduce them.
It wasn't always like this. The first guns for soldiers were far inferior to bows in utility; but we stuck with them, and now almost nobody would think of using a bow for war. We need to reignite excitement at potential, rather than pride in achievement.