Add into it the cheap air fares, etc… and it opened up the world to the average Joe, who has not the best manners or realistic expectations all the time.

Should only rich people should be able to travel? People with more money also have more manners?

add in the fact there are too damn many of us on this planet that anywhere remotely interesting to visit is packed from dawn to dusk and it gets annoying having to wait for things all the time

Just dropping this here: Debunking ‘overpopulation’

There is a football stadium near my home. Those fans should all stay home. I bet some don't even come from my city. They make public transit busy when there are games! Why do we have to share this world with others?!

EDIT: I don't want to seem like I entirely disagree but again, capitalism and mass tourism. Social media is also to blame. Societal hype. But if you think you have to wait everywhere that's "worth" visiting, maybe you can try to spread out. We don't all have to go visit the Eiffel tower or the same national park in Croatia.