"You knew what i was when you  picked me up."

The boy knew he was picking up a rattlesnake. but he also knew he was picking up a companion, and that appeared to be important enough to him to ignore the strong probability of getting bit.

people have a funny way of being blinded by their wants and needs, causing them to un-know the conventional wisdom that protects them. 

drug addicts know what drugs do, but they need to feel better. just as entrepreneurs know what the road ahead of them looks like, but if they want the fruits that come with that labor bad enough, they'll die trying.