Why do people have pride?

“Pride”, like so many terms, is very vague. In a broad sense, it simply refers to a sense of self-respect, and without it we would have no motivation to do “good” (another vague term). When you do a good deed, you do it because you need to be able to think of yourself as a good person; without that pride, there would be nothing to lose by doing whatever you want. It is only when pride becomes a conviction that you are a better and more deserving person than others, or when it leads you to overreach you capabilities to the point that you do harm to yourself or others, that it becomes a dangerous thing.

@Jayne lurve.
@lefteh 42 does not apply. It is the answer to life not the basis of pride.

To make Shame meaningful.

so they have a justified reason to feel oppressed and to also oppress somebody else

For some people it might look like pride. For that person it could be confidence.