The reason is the x999 bet possibility.
With the minimum bet of 0.002 BTC, you get almost 2 BTC!!
Well that case is not for me since I mostly like played on blue or green line although I'm just make a small profit rather a loss
there is chance to lose even if you play with green which got only 1 0.4x there, and blue got 2 0.2x so the chance is always there to lose, and it is random
Chance to lose on green is big 19.6% and chance to win is small , same situation with blue where you have 13% chances to lose but small chance to recover your loss