I dont think 1.65x martingale is a great multiplier on it. It just depends on your luck when it comes to dice game. What I can say it 2x multiplier is the best thing to do. Because if you win it will double it. Let say base 1btc 2x you will get 2 btc then if you lose you will only lose 1btc. If you use 1.65x you win 0.65 but if you lose you will lose 1btc, it is not worth to bet like that. You need at least bet 2 times to double it and it will double your chances to lose