When I was younger, I was an idiot.
In more ways than one, but the way I'm thinking about today is how stubborn I was about reading specific kinds of books. You couldn't tell me anything. In high school, I refused to read books when assigned and frequently only read them after I'd failed the test.
I thought Harry Potter was stupid for the longest time. I considered Stephen King too pedestrian. Horror was for morons, kids books for dimwits, mysteries for old ladies, biographies for old men, romances for women, and literary fiction for snobs. I mostly read sci-fi/fantasy or obscure philosophy books. In short, I was an idiot.
With age, I've seen the folly of my ways. I've read some Stephen King, fell in love with the wizarding world of Harry Potter, cracked open some great Agatha Christie, and even read some books that might border on the romantic. Right now, the hot trends in YA are dystopian fiction and paranormal romances. Neither of those are my particular cup of tea, however I've read some really great ones. The Hunger Games trilogy stands up as one badass set of books, and Dia Reeve's Bleeding Violet is one of the sexiest, funniest, freakiest paranormal's I've ever had the pleasure of reading.
I think that people who cut themselves off from particular genres on principal are doing themselves a disservice. I almost didn't read Lauren Oliver's Before I Fall because it felt like a chick-lit kind of book to me. And I'll be honest: all the mean girl nonsense was a huge turnoff to me. However I'm glad I read it because it was beautifully written and well plotted and Oliver achieved what she'd set out to do in a really great way. And at the end of the day, I'm glad I read it.
And it goes doubly for writers. If you write, then every book--good and bad--has something to teach you. I may not be a fan of Dan Brown, but the guy knows how to spin a story. Agatha Christie may seem outdated, but she can set up a mystery. Being a writer and not reading as widely as possible is like going to college but only studying medieval literature. Sure, you think, I write hardcore realism, what could Harry Potter have to teach me? The answer is: everything you ever needed to know about world building.
I'm still an idiot, but at least now, I'm a widely read idiot.