How can supply and demand for different careers affect job stability and income?

Supply and demand affects the labor market just like any other market. If there is an extra supply of immigrant workers that come into the workforce and the demand for jobs stays the same then employees could have less job stability and employers would be willing pay less causing income to drop. On the flip side if demand for a job increases while supply stays stable then job stability gets higher and income could get higher as employers are willing to pay more.