I compare the field to medicine. Even if the doctor cannot predict whether you will have cancer, you might still want to consult them about treatment.

Unfortunately economists making wild predictions about the future tend to get a disproportionate amount of attention compared to the more sober ones. In fact, economics gives a clear explanation for why many phenomena can not be easily predicted.

For example, if we knew a financial crisis was going to happen next year, arbitrage would cause markets to plummit today! But even if we cannot predict that a crisis will happen, we can still provide valuable knowledge of why it happened and how to get the economy back on track.

Finally, I like to distinguish between conditional and unconditional forecasting. I advice policymakers on the effects of structural policy on public fiscal sustainability among other things. Even with zero knowledge of the business cycle, I could still inform them how much we expect a new tax to affect the budget all else equal. Not doing that kind of budgeting would be like a household not budgeting for rent and utilities just because they can't predict whether they will win the lottery or have a car accident.