I was a cryptologic linguist for the army and went through a 16 month course of 6-7 hours of classroom instruction per day M-F, native speaking instructors, tons of immersion, and a couple hours of homework each night and left still feeling like I hardly knew the language that I was supposed to be interpreting. Unless your major in college is a specific language, you probably won't achieve any sort of fluency in your…
For a randomly picked person, yes, but it doesn't matter to apps that specifically cater to motivated language learners. It's like saying "new training shoes will not make a random person run better or become healthier".
Obviously talent and motivation are mandatory.
However, any stock-market valuation right now is divorced from the success potential of the business. That's a separate issue.