One reason why the economy has to keep growing and churning out more goods and services is the high and growing fixed costs that people and businesses face. The fixed costs of rent and mortgage payments. Also the fixed costs of insurance, health insurance and even car insurance. Much of the premiums are fixed costs that necessitate a certain amount of economic activity to meet each month.
Conservatives will say that government creates fixed costs, but I think this is less the case. Lots of taxes do vary based on income and consumption.
Some folks suggest that car insurance should be based on miles driven, versus a fixed rate each month. Then folks that don't use the car as much could save on insurance.