The purpose of a 30-year fixed mortgage is to build up equity in a home you otherwise couldn't afford. If OP moves, they now only have to take on a smaller mor

The purpose of a 30-year fixed mortgage is to build up equity in a home you otherwise couldn't afford. If OP moves, they now only have to take on a smaller mortgage for their new home and then keep paying that new mortgage off. The goal is that by the time you reach retirement age, you have paid off the mortgage and own your home free and clear. Thus, you only have to pay the property taxes and have more financial security than someone who never built up equity because they always paid rent. Furthermore, if you have children, that home is potentially a source of generational wealth. They can sell it after you pass and invest the proceeds, or live in it themselves if they want. Worst case, if you find you didn't save enough for retirement, you can tap into the home equity to keep food on the table, although this is not optimal.