Bad
scheme - A large-scale systematic plan or arrangement for attaining some particular object or putting a particular idea into effect, often through deceptive means
It's better to be honest and work hard, and not spend too much time devising or falling for schemes that are tempting shortcuts to making money.
expendable - Not essential, able to be used up or sacrificed without significant loss, easily replaced or not necessary for long-term use.

The workers didn't feel any sense of job security, and they felt expendable, because they were fired whenever the demand for the factory work slowed down.