Nothing to do?dontbe kidding, everyone in the economy has a goal/objective, etc.,be it to build infrastructure, provide security, trade goods to customer, deliver services or whatever.

The only difference is that some things cannot be provided by private markets very well due to natural monopolies, positve or negative external effects and thus free rider problems for the former, or too much social injustice (like security only for the upper half of the population not being acceptable). This mix of efficient allocation and social distribution arguments is what leads to government militaries, but obviously they are an economic actor too, as is every organisation, if they like it or not.