Most people live their whole lives by racial prejudices, religious biases, and all kinds of derogatory stereotyping of others. It is a way for them to make sense of the world, and when their lives are consumed by making efforts to earn their livelihood, construct a house and raise their children respectfully, they never have the time or opportunity to learn better ways of thinking and existing. Even when people have such opportunity, and are, let's say, educated at prestigious institutes, they might never feel the inclination to explore some subjects in detail and read books or listen to informed persons, and even if they do, they cannot explore all subjects and re-learn everything around them, because we cannot always be critically analyzing everything.
In such an environment, there are always some people who are willing to cash the general opinion, however uneducated it might be, because actually CHANGING the majority's opinion is a tremendous task and quite near impossible, so they just apply a utilitarian approach, even if it is sexist, misogynistic, racist, or classist. So our politicians, our media, our celebrities, our internet sensations, our scholars, our high-end officers, all participate in it to different extents, and those whose morals do not allow them to do so, usually just keep silent and go on living their lives privately.
One has to be incredibly strong and dedicated to their cause if they want to have even a little effect on the general opinion, and even then, there is no guarantee that after spending your whole life for a cause, you would see some result.