I give my answer, it all comes down to FOCUS. NASA just on base level, now has to do far more things at the same time, only a small part of its budget is focus

I give my answer, it all comes down to FOCUS. NASA just on base level, now has to do far more things at the same time, only a small part of its budget is focused on the moon. So they have science sats, space station and lots of other things. Second is budget, NASA of course had a larger % of the federal budget but that is bad analysis as that was before social spending exploded. But even in absolute terms, during peak spending, NASA had higher yearly spending then now. Even more important is that if you are working towards a mission many project, lander, rocket, crew capsule all hit peak cost at the same time, so you will need much more money at that moment (in that year). Current NASA can't do this, they have to make development sequential. That's why NASA switched to this concept called 'capability based planning'. So instead of saying we need to do X,Y and Z to do 'Mission A'. Its we have P, L and we could invest some development in O so we can attempt do 'Mission B'. The thirds is just as important. In pure money terms, even with the reduced amount of flexibility and money because of the above, doing a moon landing is very possible. However, NASA does not have architecture freedom. Every single component of the moon landing architecture has to be separately battled for politically. NASA does not have the mandate of going to the moon and here are 5 billion a year to do it. That is how it worked during Apollo. The politicians didn't care what the architecture was. Now Congress tells NASA, you need to build a rocket like this, a capsule like this and so on. To be more specific, its totally clear to everybody who really thinks threw this that SLS/Orion make very little sense. The US has a grown fleet of commercial rockets that can launch pretty large payloads to LEO. And soon NASA will have access to multiple providers for both human and cargo (pressurized and unpressurized) transportation to LEO. So up to LEO NASA has everything it needs. What it really needs is some craft to go from LEO to LLO (Lower Moon Orbit) and then a Lander to go up and down to surface. Those could be the same craft. NASA has to pay nothing of their yearly budget to have the ability to put stuff and humans into LEO. So really their 4-6 billion $ in budget should be 100% focused on how do get that cargo (including human) from LEO to the moon. Instead SLS/Orion cost 4-5 billion $ per year, and the result is only a tiny amount of cargo can go to the moon, and not even to LLO. How to use those 4-6 billion $ to do that is up for debate. There are multiple answer that would work just fine. Depots and reusable tugs. Mega lander (like Starship). Assembly in moon orbit. All would be doable if you could spend 5 billion $ a year on it. NASA is not the moon lander agency now. NASA is the do these 100 things and do it the way congress wants them agency.