You Don't See Objects, You See Things You Could Trip Over

The brain produces positive emotion when it sees an open pathway toward a valued goal. The more valued the goal, the more positive emotion you see when you see an open pathway to it. And that implies that open pathways are important. It implies that valued goals are important. That's why drugs like alcohol and nicotine or kaffine can make you feel useful as if you're doing something useful. They activate the system that's activated when you perceive a clear pathway to it - which is why they're addictive.