You can successfully learn a language for a bad reason. Suppose you learn a language because you think it'll improve your economic prospects, and then your economic prospects don't improve. For instance, you get a degree in language X because you think it'll lead to a good job, only to wind up getting a job that you could just as easily have gotten with no degree at all or with some Mickey Mouse degree that would have required a lot less time and effort than your degree did. And then you regret ever having bothered with X. But if you learned a language out of personal interest, and that language does nothing to improve your economic prospects, that doesn't mean you were wrong to learn it. If you got what you were hoping to get, then all is good. But there are plenty of people who think that languages are a chore that should only ever be bothered with as a means of improving one's economic prospects. And then if they see someone who learned a language for some other reason, they conclude that the person made a stupid choice. And that's just silly. You might as well argue that playing basketball is a waste of time unless you're doing it professionally or hope to do it professionally.