The reason why they don't change course is because there are multiple actors involved and a few of them go along with the powerful who they believe have the wrong proscription out of hope that eventually they will come to their senses.

But this is a fool's game.

Even Varoufakis believes (with his constant beating of the drum for Eurobonds) that eventually Germany will change course. But it will never happen, not until it is way too late.