Fear of offending the more powerful and internalizing the “moral” hectoring they deliver at every opportunity. Guaranteeing bank profits is somehow more “moral” than the health and well-being of entire countries. Social Democrats have absorbed this ideology as thoroughly as conservatives.With the Empire's neoliberal agenda and forces arrayed against them, ordinary Greeks need all the help they can get to keep from being crushed by the forces of fascism, aka the naked fist of capitalism, which are now facing them.
Socialism in one country is not possible in one small country. Socialism in a single big country would be extremely difficult, if the entire might of the capitalist world were arrayed against it.
There are no Greek solutions for Greece, there are only European or international solutions.
Nonetheless, somebody has to go first. Finding allies is indispensable for any Greek turn from the eurozone to have a chance at success.