To your question: why would Assad gas his own people when he is winning the war? Why indeed? And why would he gas his own people period? Like him or not, he was elected by the Syrian people, like Trump was elected by the American people. It makes about the same sense as Trump gassing his own people.

None of this makes sense. Pretexts to attack another country do not have to make sense. For starters, the gullible majority will not even think of questioning CNN, FOX, MSNBC information and will not conduct their own independent research. Plus with most people having at best a three-second attention span, by the time they hear a new sentence, they have forgotten the content of the last sentence. Put that together with lack of critical thinking, lack of knowledge and lack of interest in learning, they will swallow as much shit as you care to feed them.

We will not intervene in the Middle-East.
Let's bomb the Middle-East.

Isis is bad.
Let's finance Isis.

Assad gasses his people. Let's punish Assad for his crimes.
Saudi Arabia has Sharia law, kills gays, veils women, is destroying Yemen. Don't be such a racist islamophobe and look at the beautiful orb.

Israel is persecuting the population of Gaza and squeezing them out of their own land.
Jared, pass me the challah and let's make Jerusalem their capital.

Logic?
Consistency?
Decency?
Humanity?
Forget all that. We want oil. We want petrodollars and we want to rule the world, even when there is none left to rule.