Yes that is true, because there is not strategy that is profitable. There is no set of fixed rules that will result in fixed profits. The market is flexible, and somewhat unpredictable. The only way to gain profit from a market is to analyze macroeconomic events that will affect it.

The EV will be uncertain, but the risk is easier to calculate than the reward, so there is material we can work with. In quantitative finance, there are many topics about this.

Also in betting it's pretty easy to estimate the winrate, that is what the sportsbetting bookies are doing, and they are good at it, otherwise they would be bankrupt.