> But evidence shows that they do emigrate in mass when there's a reason

If you go to the CNN website there are lots of articles on there right now (e.g. https://edition.cnn.com/travel/us-woman-moved-to-germany) about US peeps who have emigrated to Europe recently and are thoroughly enjoying their new life with no plans to return to the motherland in the foreseeable future.

I can't possibly think why. ;)