I've never been on a cruise ship. Come to think of it, I never had a desire to be on one.

So, what are the devastating consequences for the citizens in the popular city?

I think you are correct about negative consequences of mass tourism. A large number of people are taking insane trips that seem to be more about creating a list of the places they've been than learning about different cultures.

Knowing nothing about cruise ships, it seems to me that they should be a relatively benign form of mass tourism. People party on a boat for two weeks with the vast majority of their time spent on the boat.