#tl;dr: No trauma connected to The Mushroom Kingdom itself. It probably has a REALLY good economy and free health care

[pianokantzart]

Seeing all these post-movie scenarios about how deep Mario and Luigi’s trauma could go, I’m surprised they (especially Luigi) would even want to return to the Mushroom Kingdom, let alone eventually live in it, after everything they went through. If I gone through what they had, I would never want to set foot through the pipe again.

As much as I love that the fandom collectively agreed that Mario and Luigi were deeply traumatized by the adventure (rightly so), I think Mario ultimately fell in love with the world and Princess Peach despite everything.

He was clearly awestruck from the moment he stepped foot into The Mushroom Kingdom, and by the end he was engaging a sentient nuke in a dog fight to save it despite the fact that Luigi was safe and out of the blast zone at that time. He got attached.

Luigi, for all he went through, has no negative experiences connected to The Mushroom Kingdom. His entire "adventure" took place either in The Darklands or on Bowser's floating fortress. I don't think he even set foot in The Mushroom Kingdom until the very end of the film. And of course, wherever his brother is happy, he's happy.

As for the warp pipe... I think there's a reason why at the end of the movie, Luigi waited for Mario to jump in the pipe ahead of him and stayed as close as possible when he jumped in after.

There might be a bit of anxiety there, but they're pressing through it.