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Problem is that it's a super difficult language where you can't draw any help from any other languages you might now. Plus it's obscure and if you move out of Finland you'll likely never use it again. I can see why people don't want to invest huge amounts of time learning it unless they plan to stay for the rest of their lives.
Actually, the foundation you got with Finnish should be useful if ever you need to learn Turkish, Hungarian or Japanese. Natural languages are like programming languages in a sense -- Haskell doesn't get as much use as C++ but learning Haskell will make you better at C++.
Yes, there are grammatical similarities, no that won't help you much at all in understanding or talking to people...