The core paradox of retail Forex lies in the execution model. Most popular brokers act as "Market Makers" (B-Book). In this model, the broker does not pass your trade to the real market; they act as your counterparty. When you lose money, the broker earns it. This creates a fundamental conflict of interest.
To maximize profits, unethical companies utilize technical tools like artificial slippage, "stop-loss hunting," and spread widening during high volatility. Even a license doesn't always prevent these practices if the regulator (often offshore) ignores them in exchange for an annual fee.