Its not true Stephen held all the cards or "shared" the winnings.
Rachel could have taken the winnings in the round where Faraaz voted for Stephen. At that stage, both traitors had a real opportunity.
Rachel could have voted for Stephen, assuming Faraaz would do the same (as he’d told her he would). With Stephen voting for Faraaz (not Rachel, as promised, and very unlikely Jack) and Jack voting for Rachel, Stephen would have been eliminated.
Equally, Stephen could have taken his chance in that same round by voting for Rachel. He knew Jack was voting for her. If Rachel had voted for either Faraaz or Jack (i.e. anyone but Stephen, as promised) and Jack voted for Rachel, Rachel would have gone out.
In both scenarios, success depended on others voting as they’d indicated. If someone didn’t, it could easily have ended in a tie — and it would have been especially awkward if both traitors had turned on each other!
Rachel did extremely well to reach — and survive — the final. The only real luck she had was being selected in the first place and getting the box with the shield. Everything else was her ability to adapt to events and turn them to her or Stephen's advantage — something Stephen also did well.
I wasn’t her biggest fan at the start — she lacked a fun side — but I really enjoyed the outcome. Both traitors stayed as true to their word as the game allowed, and neither dragged a Faithful to the very end on a lie just to reveal they’d been used.