Learning Finnish/Hungarian?

I have always had an interest in learning Finnish, and recently I looked at Hungarian and it looked pretty cool, but they aren't practical at all. I am learning German and am approaching intermediate level, and that will be useful, but both Finno-Ugric languages are pretty useless. I think I just want to learn them because they sound interesting, and because they're supposedly the hardest languages to learn, because they both have really complicated grammar. Am I crazy for wanting to learn them mostly because they're difficult?

You're not crazy for wanting a challenge. (If you want a challenge, Finnish and Hungarian will certainly provide one.)

But if it won't be useful to you, it's possible you'll just lose interest.

If you're looking for a challenge, but don't necessarily want to study any Finno-Ugric languages, then how about studying Latin, Arabic or Ancient Greek? They're very challenging as well, and at least Modern Standard Arabic can be somewhat useful, and if nothing else Greek and Latin will give you an appreciation for all the loanwords English has got from them (plus Latin can be very useful if you're going into medicine or law).

Of course, if you really want to learn Finnish, then how about buying a cheap used textbook first, dabble in the language a bit, and then decide if you want to pursue your studies seriously?