The machines can force a loss, but they can't force a win. If you're unlucky you're unlucky and the machine will make it up by not forcing losses later with someone with more luck and skill. Statistics give enough opportunity to not need to rig every game, and they only need to achieve a ratio over a long run, usually millions of plays ('we' always ran to 3 million plays as our statistical target, but that was fruit machines, aka slots).