soldier of fortune

noun2

1. •
   A noncommissioned soldier willing to serve any state or person who will hire them.

   • Today, still wanted by the government, they survive as soldiers of fortune. If you have a problem, if no one else can help, and if you can find them, maybe you can hire the A-Team. — 1983
2. •
   (figurative) A person willing to work for or ally themself with any person or institution who will hire them.