I have always been told that German is a difficult language to learn. So when I was young I opted for French instead as it was familiar to the Italian I heard on TV!
Now I’m in Berlin studying German and I understand why German is difficult: because it is unknown, because it is not familiar territory! It is not the language itself that is difficult. I believe that no German feels that their language is difficult. As much as no Chinese person feels that Mandarin is a difficult language.
But learning a language that has a new structure makes one think about reality in a different way, makes one structure reality different and process one’s thoughts differently. And that is the difficult part. And the learning process first involves trying to understand the new language by forcing it into the language structures one knows, until one achieves a level of proficiency where one starts thinking in the new language structure. It is no longer a foreign language at that point because they have inhabited it.
Which makes me believe that people who learn different language structures have an opportunity to be more open to different experiences because they have to interpret reality in different ways when switching languages.