Not unlike the 30 years war, the civil uprising in Syria started for one reason (democracy), yet has been transformed into something completely different - in fact several different things.

At one level, it is an enormous decades-long wider regional grudge match between Iran (and its proxies) against Saudi Arabia (and its proxies).

It is also about Turkey's (or AK's) determination to re-build the Ottoman Empire from Beirut to Basra.

It is about Russian trouble-making opportunism.

It is also about a long struggle by the Kurds to establish a national homeland, and the Turks determination to prevent that.  How determined?  Turkey let Aleppo be destroyed rather than let the Kurds break the siege by driving west of the Euphrates to Aleppo.

Turkey refused to allow that, first, because they do not want a Kurdish state; second, because it would have cut IS/ISIL/Daesh off from its support and its oil market in Turkey.  AK arrested and imprisoned journalists who tried to report on this.