For people in general these data brokers are a primary source of information for spammers, both political and semi-targeted. So they share responsibility for making calls from unknown numbers useless.

Depends on what kind of life you live, daily. If you're totally inoffensive and not being bold about anything, not interacting with people in meaningful way, such that no one could possibly be motivated to use the information to track you down and hurt you, then, practically speaking, you're too boring to be of note. But if you are interesting to someone. Maybe you're the other person in an affair, or you're active online in some sort of fashion; if you stick out in some way, then they, whomever you've pissed off, is gonna track you down thanks to such data leaks. Personally, an ex girlfriend just got into a fight with her latest beau, and for some reason I came up, and he was able to track me down to tell me exactly what he thought about I don't know what. Not having that information out there would make me safer when the woman at the bar I made out with turns out to be married to a jealous and violent police officer.