mercenary

One motivated by gain, especially monetary.

J. Argyrofylus, a mercenary Greek, who came to teach school in Italy, after the sacking of Constantinople by the Turks, used to maintain that Cicero understood neither Philosophy nor Greek

Such a man emphatically deserves the name of fortune-hunter—a wretch as detestable in society, as destructive of domestic happiness! And if, when marriages are consummated on such plans, there be afterwards between the parties the least appearance of regard, and the common forms of decorum, it is more than can reasonably be expected, and infinitely more than such mercenaries deserve.

A person employed to fight in an armed conflict who is not a member of the state or military group for which they are fighting and whose primary motivation is private gain.

He exhorts the emperor to revive the courage of his subjects by the example of manly virtue; to banish luxury from the court and from the camp; to substitute in the place of the Barbarian mercenaries, an army of men interested in the defence of their laws and of their property

If a mercenary died, that was one fewer man to pay. Mercenaries were an efficient way to run a military campaign especially in view of the employer's ability to hire and fire when and if the situation demanded

One hired to engage in a figurative battle, as a corporate takeover, a lawsuit, or a political campaign.

Motivated by personal gain.

Success is never so interesting as struggle—not even to the successful, not even to the most mercenary forms of ambition.