Hi everyone!
Big thanks to sunnybeacher for allowing me to review a vouch copy of the script.
The script is legitimate, although I wouldn't go so far as paying for it. It is basically the original martingale.js script --
https://github.com/bustadice/scripts/blob/master/martingale.js -- with only the parameters modified.
Martingale is based on the idea that you can't lose too many times in a row. Every time you lose a bet, it doubles the size of your previous bet, to try to "make your money back".
Of course, as with all provably fair gambling, there are no "strategies" to winning money and, due to the house edge, the expected loss exceeds the expected gain.
Nevertheless, I deposited 0.001 BTC to test the script and then cashed out at 0.003 BTC. Your result would likely be much different, though -- you must keep in mind that you are expected to lose money, and the chance of this rises with the more times you wager your money.
If there were truly "insane earnings" to be made, then you can be sure sunnybeacher would be wagering himself instead of trying to sell you the script. But, I wouldn't go so far as calling him a scammer or anything.
https://en.wikipedia.org/wiki/Martingale_(betting_system)
https://en.wikipedia.org/wiki/Optional_stopping_theorem