Competitive gamers - or at least the kind that get big Twitch viewership - aren't too far removed from athletes. They're used to the game giving reliable feedback and to getting as many tries as they need to perfect their skills, even if there are moments of high pressure to test them. They're rewarded by chasing a big audience and hustling to put up equally big and obvious leaderboard scores. Gamers have "tight grips" on their domain and optimize themselves heavily towards crushing the game. It's not just an IQ thing, but a personality type.
Finance tends to be the opposite - limited information, long time horizons, optimal risk/rewards by going into poorly understood niches, and permanent failure making loose attachment and adaptability preferable to optimizing. While you can make the competitive gaming mindset work, it's an "attack dog" way of running your life.
And you can see a contrast between session based online gaming - which is what gets most of the Twitch viewers as alluded earlier - and MMOs, in the types of playstyle that "make it" competitively. While MMOs often reward persistent grinds, they can also reward creative ways of redefining the game's goals and mechanics to develop the game in a pro-social direction. You want to be in an MMO with other people who know how to make the game lively, not 1000 angry sweatlords chasing after the same leaderboard stat. So there are typically more ways to measure oneself, and more opportunities to do things like item trading arbitrage, which is directly financial in nature.