Economics teaches humility because it teaches us more about what we can't do than what we can do
If you bound the arms and legs of gold-medal swimmer Michael Phelps, weighed him down with chains, threw him in a pool and he sank, you wouldn't call it a 'failure of swimming.' So, when markets have been weighted down by inept and excessive regulation, why call this a 'failure of capitalism'?
We do not need to understand economics in order to experience the benefits of freedom of exchange and production. But we may very well need to understand economics in order to sustain and maintain the institutional framework that enables us to realize the benefits that flow from freedom of exchange and production.
The natural proclivity of democratic governments is to pursue public policies which concentrate benefits on the well-organized and well-informed, and disperse the costs on the unorganized and ill-informed.