I don't think we're blaming ourselves at all for what happened in Syria or the formation of ISIS
The Syrian Civil War was a Syrian Civil war. They started it themselves after they saw Libya oust their dictator and wanted in on the action.
Really, the US had very little influence over it at all
We had good reason for not supporting Assad at the beginning. When protesters formed and asked for fair government, he responded with bullets and bombing his own civilians. That's how it all started.
Then the rebels formed, then the terrorist groups formed, or others like Al Qaeda jumped in. Later ISIS was forged from the ruins of the massacred populace. When you bomb your own country to bits, this is to be expected. Assad bears the weight of that burden. Not us
Even then, the US was apprehensive about who to support. Obama could see that the Syrian people were being abused by their own leader and wanted to help by supporting the FSA. However the amount of terror groups forming at the same time caused a lot of confusion. People struggled to tell the Rebels and the terrorists apart. So decisions on who to support were hotly debated and actions suppressed.
This went on until finally: all Syrians who wanted free democracy either fled or died. Leaving behind a majority of Assad supporters in the Syria telling the world that they liked Assad. We let them have him.
The remaining opposition merged together to become ISIS
So overall. Nobody did jack shit about Assad…. and I think its because we didn't help the rebels enough that we have ISIS. Not because we helped them at all
If Assad was kicked out of office at the very beginning when the protests were peaceful, and if we replaced Assad with the government that the protesters wanted: one that was fair to both the sunni and shiite muslim populations, we wouldn't have Assad or ISIS. We would just have Syria