Because ignorance is bliss. But knowing your saving hundreds of lives a year by going vegan is an even more blissful and rewarding experience. <--- I hate this philosopher with a burning passion but I do like this quote here.
The people in this novel feel as if they are living the life , but they are being deprived of something so important. When they realize this it is as if everything comes at you at once. You'd feel as Guy Montag felt.