Regardless, even if you have a strategy that works for now, that doesn't mean it will continue to work forever. Anyone investing that isn't an expert in a particular industry in which they trade is basically just guessing. Any insight they have will almost invariably already be priced in.
The more interesting questions is "can you actually, consistently, make money if you are good and spend a lot of time analyzing the market. In other words "can you actually have an edge on the market". From what I've seen it's so but most people don't believe it.
Everyone who says that they in particular can beat the market consistently year after year, unsurprisingly won't reveal any evidence behind their claim. It's always things like: "Oh, it can be done. Trust me! There are ways! You just don't know them and we market-beaters do! You just have to analyze harder, bro."
Sure, if your sampling was unbiased. But here, it's not - so that user might well have been lucky. How many people have failed to make those returns, or any kind of return?
There's very obvious evidence that somebody can outperform the market, even to a massive degree. From what I know, there's very little evidence that a particular person can deliberately outperform the market - and daytraders, especially, cannot do so consistently.
