You are very much right about real life. But when people watch the show they see them only as contestants. Pratik appeared as a douchebag on stage and almost everyone hated his attitude. The next two days people found him irritating. Then he slowed down and started showing his good side too. The guy fights with everyone and for silly reasons but he hardly abuses or uses bad words against anyone. Now people have started poking him to get footage because he is footage provider.
About Ridhima it was the exact opposite. People expected her to be mature but she turned out to be irritating and mad. Like Shamita described her so well, Ridhima actually wants Pratik to say something so that she can fight.
It's good to fight back but not insanely and that's what Ridhima is doing. Not only Pratik there were times Ridhima instigated and poked first. Even yesterday when Pratik started talking she interrupted him but when she wanted to talk she said she doesn't want to get interrupted. Or when it was between Neha and Divya about the kala dil task why did she mention that she wanted to throw Pratik in that kala pani ? If she didn't give OTT reaction and fought back like a sane person, people would have appreciated her. Like people did initially with Neha thinking she was mature but she too turned out to be quite manipulative.