For example when you go to the Forbidden Journey attraction in the Wizarding World of Harry Potter at Universal Studios, there's a long line to wait in like you would expect of any attraction. However it isn't a roped queue that you stand in, it's a walk through Hogwarts School of Witchcraft and Wizardry. You stroll through the greenhouse filled with mandrake root and other plants that are alive before moving into a great hall where Dumbledore walks out onto a balcony and greets you then you pass into narrow hallways where the paintings on the wall are having a conversation but will stop to acknowledge your presence and sometimes insult you. You are actually so distracted with the environment that you forget you just waited an hour in a line, if felt like you were just on a casual stroll.
Contrast this with visiting the Colosseum in Rome where you show up and half the structure is covered in girders and tarps because they're performing some restoration. You get in a line that's not much more than a cattle corral packed in with hundreds of other people waiting to buy your tickets. You wait an hour nudging forward a couple steps every few minutes. The place is covered in grime and dirt. When you get inside you have to move around the thousands of of there people crammed in trying to take selfies or filming everything. Everything is behind chicken wire or metal barriers.
Venice in particular is a great example of a place that has basically become a Disney-lite type of experience. Sure the city buildings are ancient and the canals and alleyways make for a truly unique location that's fascinating from a historical point of view. But it's smelly, hot, hard to get to, utterly packed with visitors; the lines are long, the attractions aren't always what they are cracked up to be, they nickel and dime you for better access and shorter lines, you have to carefully choose restaurants and food vendors, the "shopping" is barely different than what you find at an upscale mall in any large city in the world, there are pickpockets and scammers, the rides cost extra and aren't always working, the gift shops are overpriced and often terrible quality. All in all, Venice may be more real, and if you're a history nut you can probably see some interesting settings from old stories, but if you are wanting to have fun on your vacation and experience something pleasant that you can't normally do, Disneyworld is cheaper, easier to get to, less crowded, and a lot more fun.
ADDED: You could say pretty much the same thing about many cruises, Club Med, etc. Many people like to get out of their day to day routine while still enjoying a pretty predictable and controlled environment.
I also prefer visiting different places in the world, but I totally understand people have different hobbies and like different things. It's not difficult really.
There are people who are obsessive like any other hobby. There are people who seem to be trying to relive their childhood or one they never had, over paper over some damage.
But for me, it was sort of a relaxation thing. Working a high-stress tech job, there was an implicit understanding amonghts my friends and I. You leave your troubles outside the park, and have fun.