Well, first, you have to really want it more than everyone else. I know lots of people have drive but aren't high level but that's still the biggest thing. This includes mindset and the quantity/quality of practice you get.
Then, you have to be good at analyzing the game from a practical standpoint. You have to keep an open mind at all times and be able to recognize your opponent's habits, and more importantly, your own. Then you have to be able to adapt in-game and overcome bad habits and aspects of your mindset that are causing you to either continue doing something bad or disallowing you to notice something you our your opponent is doing soon enough. Hindsight is 20/20... Personally I'm really good at analyzing videos and giving advice too high level players after the fact, but still have problems noticing the same exact things for myself in game when it counts.
Also, the amount of time you've been playing doesn't really mean much. The average smasher that starts today has a MUCH BETTER chance at improving rapidly due to the countless YouTube videos, numerous tutorials, 20XX, and the game's semi-recent spike in popularity (more tournaments, more people to practice with/fight against). The game is approached differently nowadays. I can lose a friendly match to someone and they'll ask me how long I've been playing, and when i say 11 years, they essentially say "durrr hurrr I've been playing one eleventh of that durrrr hurrrr hurrrrr" lol. And I just think, you are so lucky and will probably never understand why (then I body them of course). Those who start playing now have access to information that will essentially direct their practice and focus to the things they SHOULD be practicing. There's less theorycrafting going on now since so much of the game is figured out.
There's so much to this, but I'm done swyping words on this phone lol.
