This, I think, is a natural result of the US insurance system. Being sick is quite expensive and not being sick but being proven to not be sick is also rather expensive so people will naturally tend to avoid formal treatment longer in the hope that everything just magically goes away.

This also contributes to the amount of emergency room treatments that could have been trivially handled with earlier intervention. A boil that has gone septic is a very serious medical condition, but nearly all boils can be trivially resolved with a short regimen of antibiotics.