Regnault argued that short-term price movements were like coin-tossing: upward and downward movements will tend to have equal probabilities (of 1/2), and subsequent movements will be statistically independent of previous movements (Regnault 1863, pp. 34-38). That was a fair game, but even in a fair game a player with finite resources playing an opponent with unlimited resources will eventually lose the entirety of those resources, and if that happens in a financial market the game is over from the player's viewpoint.

Donald MacKenzie, An Engine, Not a Camera, loc. 259