I think this is a case of human psychology failing us - Confirmation Bias

I think it's very unlikely that Haejin is right as much as people think he is. It's just that he posts so much that nobody notices the ones he gets wrong.

People have a tendency to boast and cheer about the times things went well, and just shrug and dismiss the bad ones as 'one-off', and are too embarrassed to publicize their failure anyway.

So the law of averages plays out and people suddenly think he always gets it right, meanwhile, all his mistakes (which I wouldn't be surprised if they were 50%) are way down his feed after posting 20 times a day.

If anybody has actually tally'd up and noted the rights and wrongs, I'd love to see the meta-analysis of Haejin's performance, but I'm very skeptical to date, knowing how unpredictable the market can be.