To cause harm to a benefactor (especially one that one is dependent on, thus with the idea that this behaviour is self-damaging).
To abandon or betray one's supporters or principles to seek profit or other personal advantage.
To sell one's commission.
To sell one's business (with a connotative emphasis on entirety and finality).
To betray (a person), usually a close friend or family member, for personal gain.
To sell all of a product that is in stock.