Other observations of people who've actually won tournaments in these games:
1) Have a brother that plays fighting games -- or at least, a very close friend that you play a LOT. Like, every day. It's wild how many major tournament winners have this in common. Often family, but sometimes a "brother from another mother" like Wound and Ducky.
2) Go in hard when the game comes out (or shortly thereafter) and don't stop. A lot of winners have made these games a lifestyle -- and it'll be hard to waltz in and grab victory if you aren't doing the same. Long sets, more sets, tons of grinding, be it online or off. Always thinking about the game.
3) Never overestimate your own preparedness. This goes without saying, but since everyone else is leveling up, you need to constantly search for new tech, new options in matchups, etc. even when you're already on top. Sonic Fox, MK9 REO, MK9 Dizzy, INJ Jupiter and Theo have been good at this.
4) Be willing go ballsy. You have to know when to take risks, but most of the players who've won tournaments in NRS games are never the absolute safest players (unless there's a specific character with extremely broken defensive tools). You have to be willing to press an advantage in order to fluster your opponent, which is something everyone from vintage PL to Sonic to DJT have been good at. Same with MK9 CD Jr. back when he was winning. Winners have a sense for when an opponent is uncomfortable and will go for the kill.
5) Actually learn the game's fundamentals. This should go without saying, but it's ironic how rare this is. I don't care how many tournaments you go to, what kind of goals you set, or what character you play; if you don't know when to poke, when to move, how to defend, when to armor, when not to jump, what's interruptable, and how to maximize the game's engine against other players, you're unlikely to beat people who do in Top 8. This is a trait that's common to both winners and great players who didn't win, but were always close: DJT, INJ and MK9 16 Bit, Sonic, MK9 Dizzy, INJ Theo, Jupiter INJ/MKX WoundCowboy and Honeybee, Foxy, MK9/INJ Pig of the Hut, etc. If you are throwing stuff out and aren't tight on your neutral/spacing, punishes, timing, etc. it's going to show once tiy play against people who truly understand the game.
You'd be surprised how many people are skating by with offensive tech and are consistently picked apart by winner-level players when they meet. It really separates the men from the boys.
Anyway, just things I've been noticing over the last few years.