There are 'DD' authors that manage to produce good insight and get 5-6 good predictions in a row but they are quite drown in other poor DD. See the ticker GME, someone with a pristine record predicted a GME pop following a console deal before the second COVID wave. Somehow he timed it perfectly (GME / Microsoft partnership annouced less than an hour after that post). That was a good DD and people apparantly made good money. Then it was followed by a tremendous amount of other poor posts (yolos, shitpost and 'gut feeling' DD) AFTER the surge. Without any information it is rather difficult to distinguish between the 'good' and 'bad' ones. There are some people tracking performances of different authors but I did not get to see an exhaustive study that would conclude one way or another.

Edit: ok nevermind the GME DD exemple. I tried to find it to link it here, but it is now deleted. People are claiming the author was a Microsoft Insider. Disclosing that info was highly illegal. I don't know what would be the legal ramifications of trading on illegal info when you don't know that said info is illegal. But I knwo that being investigated by a 3 letters agency is something you want to avoid.

From an outsider it looks as just luck that 1 out of 100 advices is useful although I guess the relevant part is the value of that 1%. In any case I don't know if I would trust a source of information like that in any other field.

Another question from a total ignorant is, if true, how is it possible that 1% exists and then... loop and wait until next post of investments pops up in HN.

The DD (daily discussion) threads usually have more reasonable insights than the individual submissions.

No. Confirmation bias means that people who make good/lucky bets might look like sages, however even a blind squirrel finds a nut occasionally.