Why did the Arab spring back a few years ago failed for the most part, the Iranian green movement didn't get the result it wanted, but the European revolutions (such as the French revolution, Revolutions of 1848) was able to reform a continent with conservative religion views and a set of dictatorship governments into a significantly more free and liberal region?
There were plenty of European revolutions which led to terrible casualties and not much democracy, both before and after the French revolution.
- The Hussite wars.
- The English revolution of 1688.
- The German revolutions of 1848/49.
- The Paris commune of 1870.
The revolutionaries simply tried again, or they faded away when conditions changed.