I've read this 5 times. I can't figure out the relation between tourism and everything else in your post. Are you just expounding on the fact that not everyone lives an equal life in the world or is there a greater point I'm missing?
Tourism is not a special case. The same issue applies to tons of activities. We either limit these activities to a privileged few, or the activities cease to exist in their original form.
Everyone loses in the latter case.
IMO the logical outcome would be that the most trendy destinations will get more expensive, thus overpricing many tourists and regulating itself, and that it will open a new opportunity for many places which are not today super touristic.
SO everybody will be a tourist, just not at the same place.
It is already happening actually, you have much more touristic places than it used to be and the potential is huge. I mean just look how many tourists you can fit in France or Italy and imagine if Asia and Africa scale tourism in the same way. Many costs are under/mis-used. The brazilian cost could be much more used than it is right now.
This has also already happened before. When Spain got more expensive, tourism grew in Tunisia and Turkey, and there is still a lot of potential there. Eastern Europe also still has a lot of underused potential.
New touristic places just appear naturally when you have a market. Not everybody goes to Tahiti, but there is potential for some destination for everybody.
Running a lottery = limiting to the privileged (lucky) few.
Creating a reserve / national park / protected area = limiting access to the privileged (science-related, or just well-connected) few.
There's no way that everyone who would not mind to visit a carnival in Venice could fit the city, if getting there was free and instant. This is a fact of life, and I personally am fine with it. People have different priorities, so let them (us) choose what group of limited few we can concentrate on entering.
For what I cannot afford to access, VR helmets exist.
Are there other perfectly nice places that you, guy who is in some way limited in your ability/means, could go to instead of the moon? Of course there are. But the moon is off limits to you because you don't have the money to charter the mission there, or the authorization of your government.
If by used you mean "used up and robbed of any natural beauty to accomodate 'selfie experiences'", I agree.