The point of a photo is to remember something you did. Not generally the photo itself.
Why then share it? I don't share the (very few) photos I take.
Resharing someone else’s photo is not even similar to going somewhere and capturing the moment.
I should have added a '\s' to my sentence ;)
When you’re old those photos might be all you have left.
Sure, memories are priceless and they may differ for everyone. I mean, I'm old(er) and I much prefer words to images myself (I've been journaling for almost 50 years). Also, I don't care to remember seing the Eiffel Tower (even less so since I live in Paris, which is a privileged place to observe tourists), or NY, or Bangkok, or any other place in particular. I wish to remember people.
Note that I simply answered the OP question (what is the craziest thing you have seen a tourist do). I may be wrong, like I hinted to in my previous comment, but to this still is the most mind boggling stupid thing I can see people do over and over again every singled day... the moment I pass in one of those few Parisian streets full of tourists ;)