Knowledge comes with responsibility: what do you do after you know things? What do you do with the "known"? Usually the answer takes you out of the comfort zone, therefore this is why people prefer not to know. Because acting like we're not accustomed goes against our program. An interesting thing is that once the mind has been exposed to knowledge, it can't go back to what it was. So in the end, it is a matter of exposure to those things which will lead to some behaviors. Just like in a dark room. You work out the negative until you get the result that you want. Unlike the negative though, we always have the possibility to escape the dark room through knowledge. Only that some have been conditioned to think that the dark room is the only room that there is. And this is how we reach to consciousness