A "Martingale" is a failure betting fallacy, and a casino can only hope for players so stupid. It will result in a player going bust far quicker than the casino. If the bet unit is 1 at 50% odds, and the betting can continue for many rounds of doubling (say 10 rounds before hitting a limit - which is 1024x) then there is little risk to the Casino. Even a win with this "strategy" means the casino wins 1+2+4+8+16+32+64+128+256+512, and if the player wins the final bet the player's total winnings is 1 bet unit; however the player has statistically paid more in house edge when betting those amounts then the total winnings; the bets are independent everywhere except in the player's mind.

Google "risk of ruin". The profit/loss of a casino over the long term is a random walk, and there is always a very small chance that any casino will go bust. If I have a 1 BTC coin flip game and have 5 BTC in the bank, I can let a player play four times with zero risk; there is a one-in-32 chance that the player will bust me in five flips. If I let the player play an infinite amount of time, there is a 100% chance the player will bust me (at some point in the future, maybe after the sun explodes). With a house edge, I can make the risk approach zero within a normal timeline.




If I open a casino tomorrow, there is an extremely small chance that every bet ever placed at the casino will be won by the player. One would need to adjust the gaming rules and house edge to minimize the chance of casino ruin to something you consider safe - do you want a 1% of going bust; a .001% chance of going bust, etc? SD has minimized this risk while having a bankroll to pay out some very high rewards on the higher odds games.


Answering the original question, "why aren't there five million copycat Googles, eBays, Amazons?" If you do something first, and do it as good as any competitor might, there is market inertia that presents a barrier to entry for others.