You're comparing apples to oranges. Kids learn foreign languages much faster than adults, plus get a lot more support and less judgement on mistakes from adults since school kids don't operate in a highly competitive environment.
But good luck reaching proficient fluency in a foreign language in your 30s where you'll face a lot more gatekeeping especially on the jobs market. Many western nations still gate-keep careers and opportunities based on regional accents alone, let alone not being a native speaker.
And before I get assaulted in the comments with the "umm acksually I could do it just fine it never was a problem for me exceptions, YES I know it's possible, it's just much much harder, especially when you've got a full time job and adult responsibilities, compared to doing it when you're 5-15 on the school playground, playing videogames with mates or watching cartoons.
But good luck reaching proficient fluency in a foreign language in your 30s where you'll face a lot more gatekeeping especially on the jobs market. Many western nations still gate-keep careers and opportunities based on regional accents alone, let alone not being a native speaker.
And before I get assaulted in the comments with the "umm acksually I could do it just fine it never was a problem for me exceptions, YES I know it's possible, it's just much much harder, especially when you've got a full time job and adult responsibilities, compared to doing it when you're 5-15 on the school playground, playing videogames with mates or watching cartoons.