The market can falter, and can create a vicious cycle where jobs will be lost because consumer power had dwindled. Without a strong base, you cant' have an economy.
Ignoring jobs like firefighters, policemen, and teachers... The governments role in this is to create temporary/short-term jobs which pump money into the base by taking future tax guarantees (i.e. move capital from the future to the present), which help create a virtuous cycle where jobs are created. These temporary jobs are "infrastructure" jobs, building roads, bridges, schools, updating public transportation, updating electrical grids, updating water works, etc. This employment puts money into the economy because those people with those jobs have to spend that money, this gives businesses... business... so that they have demand for their product, and incentive to grow, invest, and hire new workers.