I'm not even sure living in the country helps that much on its own. The issue is that the vast majority of your language intake comes from your immediate surroundings - the media you consume, the friends you have, the books you read, the place you work, etc. I've seen a lot of language learners move to a country, take classes, but get stuck in an expat bubble. The worst part is, when you take classes, you're surrounding yourself with other non-natives.
For most major languages, a heavy immersion is possible in your home country, especially with the amount of media that's now easily available. Heavy immersion is very effective, but it's also extremely difficult to pull off. The AJATT guy[1] was a big advocate for it and was extremely successful with it when it came to Japanese, but even he couldn't replicate it for Chinese from what I recall.
If you're not going the heavy immersion route, I guess the best thing would be to just have fun with the language, pick up what you can, and accept that you'll never be great at it.
I've come to a very similar conclusion. The absolute only way to learn a language is to have an incentive to learn it, IE: to be exposed to it constantly by work, daily life, romance, friendship, IE: whatever it is that is providing the regular need for the use of the language. People who say they are bad at languages might be surprised how fast they would learn if they were suddenly forced to learn by necessity.
I think learning a language at a young age likely sets up some brain development for language learning in the future. Brains remain plastic even through adulthood, but I definitely feel like whatever language I am studying tends to fill “Language Slot 2,” if you will, which exists because of an atrocious 12 year long present-tense-only public school Spanish program.
Results from learning a language in an immersive environment are going to be greater and more justify the time spent. However, it can definitely be rewarding otherwise if cramming before a vacation or even just to remember how to clumsily pronounce “l'esprit d'escalier.”
This article is written by an American. Given the immigration rates, you have a damn good chance of finding people who speak the target language you're trying to learn quite well, and Spanish in particular can be quite easy depending on where you live, given a quarter of the country, including the two most heavily-populated states, were formerly Spanish colonies and once part of Mexico. The third-most populated state was never part of Mexico but was also a Spanish colony, and is full of Cubans.
Do you have a maid, landscaper, janitors at your office, kitchen staff at your favorite restaurant? Talk to them.
Learning rudimentary components being a waste of time may be a bit of a stretch however expecting to master the language through apps, YouTube tutorials, not using books and physical media is laughable if not delusional.
It's helpful in learning nearby languages. I am a native English speaker, and my French can approach fluency given some immersion (it's pretty rusty right now, though). DuoLingo helped me improve transactional Spanish and Portuguese (BR) very quickly, meaning I can get through airports, grocery stores, restaurants, and read news articles. I'll need something more to have free-ranging conversations or read novels, though.
Check out "The Loom of Language: An Approach to the Mastery of Many Languages" by Frederick Bodmer. I'm reading it now and it's quite extraordinary. It seems like a particularly good fit for someone with your linguistic background, especially if you have an interest in learning further Germanic or Romance languages.
So did I but, man, that took ten years of pretty intensive study (13 hours a week at the peak, across four school subjects). They taught us really well, but there's got to be a way to reach this level of proficiency with less effort.
This was in the Soviet Union and before the Internet, and so we were studying in complete linguistic isolation. When I met a native speaker for the first time, I had already been studying the language for nearly ten years.
For most major languages, a heavy immersion is possible in your home country, especially with the amount of media that's now easily available. Heavy immersion is very effective, but it's also extremely difficult to pull off. The AJATT guy[1] was a big advocate for it and was extremely successful with it when it came to Japanese, but even he couldn't replicate it for Chinese from what I recall.
If you're not going the heavy immersion route, I guess the best thing would be to just have fun with the language, pick up what you can, and accept that you'll never be great at it.
[1] http://www.alljapaneseallthetime.com/blog/