Courage is indeed a cardinal virtue.
But it usually implies that someone chooses to do something that will result in no direct benefit to them while risking everything they have in order to do it - as a matter of moral principle.
Like the soldier who risks his life in battle for the common good, and who does not expect (or usually receive) any extra material benefits for putting his life on the line.
Running against Mike Castle was not much of a risk for someone who was unemployed and looking to make a name for herself, and being elected would certainly result in very direct benefits for an unemployed consultant: a guaranteed, high-paying job for 6 years.
If only you would go after Coons’ flaws with the same fervor.