Unhealthy addictions are proof that we aren’t motivated by survival, rather we are motivated by our instinctive drives. The drives are themselves more interested in survival, but sometimes incorrectly reward us with pleasure for things that don’t serve their survival mission. So our drives may be mechanical and that part of us can be seen as some sort of ruthless biological machine, however everything we, the awareness that receives the pain and pleasure the instinctive drives feed to us, do everything we do to feel loved, needed, safe, and good.
There are therefore two parties operating inside of an organism, the awareness, and the instinctive drives. The drives receive purpose from natural selection, and they achieve their goals by employing us to work for them in return for the pleasure they’re able to reward us with.