Martingale
A system that doubles the position after every loss, aiming to recover all losses with a single win; a losing streak takes the account to zero.
In the short run, martingale shows a high win rate and a flat equity curve, then blows up in a single streak. The "grid" and "averaging down" variants carry the same risk.
Prop firms and sound risk management rule it out; small, fixed, defined risk is the only sustainable approach.