We send probes to Mars, but haven't tried to get back to the Moon in 45 years. The Moon would have been a far better place to stay than the ISS.
Why did we lose our Space Shuttle? and have to bum ride on Russian Rockets, that Russia is building in the hundreds, if not more, to get to the ISS?
If we were ever serious about a manned trip to Mars, the Moon would be far better to be the launch.
The one drawback about colonizing the Moon, it would be a security threat to the rest or the world, and especially to China and Russia.
Other than that, everything that we do is expensive, and even more expensive when we wait decades to finally do it. The US can't even get a High Speed Rail system for the 21st century, when many countries, and especially China have extensive High Speed Rail systems.
Delay has already projected a doubled cost for the planned! High Speed Rail in California.
NASA has been downsized and now they require the help of private space companies, like Space X. The original space shuttles, actually never left the Earth, but anyway they were built in the 1960s. We haven't really done much advancement in rocket propulsion since that time, and yet we can get a probe to that was built several decades ago to travel to the outer most parts of our solar system.
If some people can't think of good reasons to go to the Moon, then we need more imaginative people in the world.