Yeah it always fails in the end. I used doge-dice for awhile and and used really small percentage of my total, but eventually the house always wins. It can take a long time though if you use really small percentages of your total. I got over half a million bets before going bust.
Yah its easy to test a martingale stategy with dogecoins since there are so many of those
Although not sure what sites you can use now that doge-dice is closed for a while.