As someone who also speaks four languages, I agree with most of your post but here are some more advantages I can think of:
* Access to more media
I regularly consume newspapers, subreddits and similar in other languages to get different points of view on things.
Then there's literature and films (especially the ones that don't have translations)
* Ease of travel (this is highly dependent on the languages you know)
* Connecting with people.
Simply switching to someone's native tongue gives you a familiarity with someone that takes much longer to get if you're speaking their 2nd (or 3rd) language.
* Bragging
Especially in the US/UK you'll get a lot of positive comments from people because they think you're some kind of genius (which the study above disproves...)
Before I started working, I thought knowing this many languages would be helpful in the business world, turns out I have barely ever used them as the working language is always English.
I speak three and echo the above. English gets you most of the way in most places, but you can form stronger connections if you can meet others on their home turf instead of making them come to yours.
Might not afford you IQ points but it does afford you diplomacy points.
But these are confounding factors related to your socio-economic status. You're probably smarter than someone who is too poor to travel, uneducated, and who will die in the same village they were born. But it's not because you know more than one language.
* Access to more media
I regularly consume newspapers, subreddits and similar in other languages to get different points of view on things. Then there's literature and films (especially the ones that don't have translations)
* Ease of travel (this is highly dependent on the languages you know)
* Connecting with people.
Simply switching to someone's native tongue gives you a familiarity with someone that takes much longer to get if you're speaking their 2nd (or 3rd) language.
* Bragging
Especially in the US/UK you'll get a lot of positive comments from people because they think you're some kind of genius (which the study above disproves...)
Before I started working, I thought knowing this many languages would be helpful in the business world, turns out I have barely ever used them as the working language is always English.