Survivorship bias
The distortion that appears when only the accounts or strategies that are still running get seen, and the ones that failed disappear.
A signal marketplace or a public track record only shows what is currently live. Strategies that blew up an account are usually taken down, which leaves the pool of visible records looking healthier than the full population of everyone who tried the same approach ever was.
This is why a backtest or a short live record, on its own, cannot rule out the possibility that it is simply one of the survivors of a strategy type that mostly does not survive.