same can be said about just about anything, no? running marathons, startups, cooking a great dish... No one on WSB is saying its for everyone, thats why they talk trash about themselves.
In the long run, statistical iterations (that you have modeled/researched correctly) will give you positive returns with a very high confidence.
Situations like in this post are obviously not that. I have a trading strategy that I execute over hundreds of trades per year based upon financial modeling and financial statement analysis. There's a little luck involved, but over many trades, the luck aspect cancels itself out.
It's like rolling the dice. If you bet on getting a certain number, and roll once, it's luck. If you bet on averaging a certain number and roll 1000 times, there's virtually no luck at all.