Self sabotage

Humans have a strange ability to self sabotage. We all know how to eat better than we do. We all know how to drive better than we do. We all do things that we know are bad for us, will stop us achieving what we want, will make us feel unhappy. And yet we still do them. Why?
What is it about humans that makes us self sabotage? I'm not thinking about suicide, that is a different issue. I'm talking about buying chocolate when you have diabetes, smoking when you know it is going to kill you, not exercising when your cardiologist tells you you must.

How can people be so disconnected from their own behavior? Take a simple thing like eating fruit. We all know we should. There is not doubt about the health benefits. Fruit is delicious. And yet, we leave the fruit and take the pastry.
I see clients who tell me that they want to stop smoking. It costs them money, makes their clothes smell, makes them outsiders, will certainly make them ill, and most likely will kill them. And yet they keep on smoking. They sabotage themselves. They stop for a while and then start again. Part of their mind is screaming at them to stop, and part of their mind rejoices in taking the next puff.

It should be simple. Just don't buy any more smokes. That's it. But it is like exercising: we all know we should, and we don't. We all know we are putting on weight, and somehow we don't care. We should get on and finish the school assignment, clean the house, tidy the garden: we know how to do it, we know it needs done, and yet we don't.
Procrastination is the name for not doing something we should.
What is the right word for keeping on doing something we shouldn't be doing?