I'm talking about multiply BTC here.
Most of the time my high rolls end up in loss. Even with 94% chance to win, you end up losing your bet on the first go. Sometimes I feel they are not playing fair.

They change their server seed every time you roll. You can randomize your client seed in Auto bet. You can verify every bet on the website.

Ultimately, You couldn't control any of the rolling factors that don't look fair to me. There must be at least one factor that we should control.