Screencap this.

Marnie is Chairman Rose's daughter. He wants her to win the Pokemon League and is providing financial support to Team Yell, in order to support her. He also has paid Bede to take down every competitor in her path, and then lose to her in the finals. This is Bede's "dark secret."

Marnie is completely unaware of this, and is trying to win the League on her own ability. The moral of the story is that money can't buy happiness.

You heard it here first, folks.