Why Does Everyone Always Have To Save The World?

In speculative fiction (especially fantasy) there is a continuing theme of characters doing these great, impossible things whether it be saving the world or overthrowing a government. While I love these stories and hold them dear to my heart, I wonder why the plot of these books has to be so grandiose. Why can’t someone just protect their town from raiders or fall in love and start a family? I guess my real question is why aren’t there more stories on a smaller scale?
There are tv shows and movies that are basically about nothing more than unusually interesting everyday lives. Take Seinfeld for instance- it’s about four friends that just have the problems of normal people, albeit sometimes strange problems like death by postage stamp glue. There are so many television series like this, but to my knowledge there are few to no books like this. I would have loved reading books about magical schools where students are just there to learn magic and don’t end up stopping a dark lord. Many book series start out on a small scale- take the Alloy of Law by Brandon Sanderson for instance. Wax and Wayne are just trying to adjust to city life and try to find out who’s behind a series of curious train robberies. It’s exciting and page-turning. As the Wax and Wayne books go along, things get more fantastical and suddenly the pair is mixed up with Harmony and ancient creatures that have resurfaced from the previous books. Don’t misunderstand- I love these books immensely, but there’s a trend where characters are always in situations that escalate them to the forefront of conflict, society, and politics.
I think I enjoy the beginning of book series’ because they start out simply, with reasonably fixable problems. As many series go along they just get ridiculous and that is a discussion for another day. Yes, it’s fiction, but it can still be believable. Characters can have reasonable flaws or struggles rather than being totally broken or totally perfect. I can’t be the only book worm out there that feels this way. If anyone has a book or books to recommend that keep things *real* then let me know what they are! I’d love to read them!