>it just seems good for your brain and interesting for how you think about the world.

I am fluent in 3 languages, and while it is convenient, I assume claims about it being "good for your brain" are just as pseudoscience-y as all the other claims about what is good for the brain.

One of the languages I know doesn't even use a Latin alphabet, and I spent many hours learning it when I was little. And it's basically useless (obviously just my experience) except for communicating with older family members. Once they pass away in ~3 decades, I doubt I use it again.

Actually, the biggest incentive for me to teach my kids that language is so that we have a secret way of communicating in public (in the US). But I have failed so far, because it's just a lot of work to teach kids another language when you and your spouse prefer to speak in another, and so the kids are not completely immersed in it.

I’m not sure why you assume studies on what is good for your brain are pseudo science.

A quick google search finds several studies about the benefits of multilingualism on the brain.

Here’s a recent one: https://www.fens.org/news-activities/news/speaking-another-l...