I know data privacy is important and I know that big corporations like Meta became powerful enough to even manipulate elections using our data.
But, when I talk to people in general, most seem to not worry because they “have nothing to hide”, and most are only worried about their passwords, banking apps and not much else.
So, why should people worry about data privacy even if they have “nothing to hide”?
Even if you have nothing to hide yourself (which, as other commenters said, is very unlikely), and can be certain you’ll never have anything to hide ever (even less probable), there will be other people who do have something to hide. That does not mean they are evil (though some are) - maybe they are fighting for a cause, or maybe they are persecuted minorities, or maybe governments and/or powerful organizations will want to bring them harm.
These people, being mere humans, have some minor secrets in their past or present that can be signal-boosted by a malevolent agent to seriously hurt them, their reputation, and/or their social standing. And even if they did mange to obtain the level of sainthood that the have-noving-to-hide folks seem to possess - their perfectly normative personal information can still be used to dox them or retaliate against them in some other way.
If you care about these people and/or any cause they may be fighting for, then you don’t want them to be the only ones who demand privacy. Because:
This will make it much easier to persecute minorities and to retaliate against activists, making society as a whole much worse for everyone.