Chelsea sold their "soul" when they became Chelski. Not because they became the richest club in the world, but because of all the glory hunting football tourists that started invading Stamford Bridge that do nothing to cheer on the players, as most of them don't even know a bloody word English other than "Ai Sooportttt Chelskee, ja?"
The soul of a club is the fans. And the day there's no more fans singing in the stands, but it's still a packed stadium. Then you can say a club has lost its soul.