Enjoyment is an advantage
With so many people in the world and on the internet, if you really want to be a top performer at anything it has to be a game to you. It has to be fun and genuinely bring out your curiosity. Just another reason to do what you genuinely enjoy. (Although alternatively you can get to this place through competition and wanting to be the best to be the best, but that seems to come with lots of problems and neuroses and dissatisfaction once you actually do what you were trying to do)
The marginal impact of you working on any seemingly important thing, like being a doctor is very small. There are a lot of doctors, and a lot of doctors who would have a similar amount of impact as you if you didn't become one.
The most likely way you're going to have a big impact somewhere is if you genuinely love what you are doing. How could someone compete on the same task with you if you're having fun while they're struggling?
Maybe some wishful thinking here, but I still think it's the most useful and practical way to think about it. It doesn't seem worth it or realistic to me to do something with high impact that requires tons of time and energy that you don't enjoy.
If you're having fun doing the same thing others struggle through then you're winning right now and you're going to win later.
Specific knowledge is found by pursuing your genuine curiosity and passion rather than whatever is hot right now. Building specific knowledge will feel like play to you but will look like work to others.
Following your genuine intellectual curiosity is a better foundation for a career than following whatever is making money right now.