No one deliberately chooses what they know to be evil. They merely choose a perceived good over a true one.
For example, no one chooses to murder someone solely because it is bad. They murder someone for a perceived good (pleasure, vengeance, money) or to remove what they see as a greater evil (kill a witness to avoid prosecution, get the insurance money to keep from going broke, remove a competitor or inept business partner).
They blind themselves to the worse evil in order to chose the perceived or lesser good. No one sets about to choose what they KNOW is evil; they set about to choose what they think is good.
The knowledge that human worth exceeds all temporary gain, means that murder is never the highest good. (We’re not talking about self-defense or justified force here, we’re talking about deliberate murder.) The knowledge that refraining from murder is a higher good than any excuse ever used for murder leads to the HIGHEST good, which is refraining from said murder.
Ignorance of the highest good leads to evil – through evil being called good. Every excuse for sin uses a lesser good to justify an evil. This is the sense in which ignorance is evil.