Draco has a Problem: if someone doesn't continually fight back, that must mean they don't really care who has the power in the relationship. Because he doesn't get tired of figuring out and working out the dynamics himself, he doesn't really believe other people can.

When he manages to separate his personal feelings from the situation, Lucius will acknowledge that Harry was right. If he beat him, he must be right. It's a Malfoy way of thinking.

Thank you!