It’s one things to know the right thing to do. It’s another to actually do it. And in some ways it would be better to not know, then to know and not do.
If you know what you should have done, but don’t do it, you can no longer use the excuse of ignorance. And, since you know that you knew, you also get to bear any regret or remorse that comes with knowingly not doing the right thing when you had a chance.
If you don’t know what to do, at least you can say you made an honest mistake. But to know and not do removes that opportunity, and makes us even more responsible for the consequences.