board the gravy train
To come into a state, position, or job that allows one to continuously gain or draw upon a significant amount of money without expending much or any effort. The settlement of this lawsuit will help me to board the gravy train. My brother boarded the gravy train by marrying into a family that owns one of the largest oil companies in the world.
board (or climb on) the gravy train
obtain access to an easy source of financial gain. informal Gravy is an informal term for ‘money easily acquired’.