Whenever Cena fights someone I feel like the crowd would rather see Cena lose than see his opponent win.
"Let’s go Cena/Cena sucks" is not cheering for Cena’s opponent, that’s cheering against Cena. And that is why Cena is still bigger than anyone else in WWE. Everyone seems to want Cena to go but they love to hate him so he’s clearly gonna stay. People pay to boo him and hate him.