not only that but also the increased opportunities for new knowledge and experiences as well... it can open a lot of doors that would ordinarily be shut-off.
Having achieved a foreign language college major with minors in two others I find it hard not to be cynical about this unless the doors you’re talking about are things like vacations, entertainment, and similar amusements. From a work perspective it has not done much for me. Of course that could be different if my native language weren’t English or I didn’t work in the US, but then that’s just about the relative economic importance of various languages and not some inherent property of multilingualism.
for me the rewards to learning (basic) German have been more personal than professional - attempting to speak with a German speaker in their native language generally makes it easier to bond with them.
Yeah that's completely reasonable, but there are a lot of people trying to sell you on career success that is a mirage. And it can be frustrating the people you want to talk with often speak English better than you speak the language you're learning, though that's more of a problem with some languages than others.