Why doesn’t Gian bully Dekisugi like he does Nobita and Suneo?

In Doraemon, Gian is always picking on Nobita and sometimes Suneo, but he never seems to bully Dekisugi. Dekisugi is smarter, more polite, and even closer to Shizuka — which you’d think would make Gian jealous or annoyed. So why does he leave Dekisugi alone? Is it respect, fear, or just plot convenience?