He's calling you a conspiratard because the real common denominator in all middle eastern civil wars stem from internal strife over religious and sectarian differences, rampant corruption, and general dissatisfaction with their governments. Most of which only serve themselves and their immediate allies (KSA, Iraq, Syria, Libya, etc).

Of course, the US, (Like the Russians, and Saudis) are out to serve their own interests. Those mainly involve providing support to opposition groups who align themselves (or claim to) with Western principles. That nowadays, seems to be anyone who isn't about to declare a caliphate and who wants to help remove what the US sees as a threat to it's interests (The Syrian government).

As it stands, the Syrian government is pretty much crippled and the country has been set back what may be 30-40 years worth of infrastructure damage, brain drain, and the loss of generations of men to army conscription on both sides. "Removing Assad" was essentially accomplished by the civil war itself without much support from anyone. The Army stands around 125,000 men strong, it's tank forces have been near wiped out, and the airforce has been decimated by losses of both pilots and aircraft. It didn't help most of their equipment was outdated and due to be retired before the war began anyways.

The point is Syria isn't a regional power anymore, and so the continued involvement of the US in supporting opposition groups is to try and save face and stand by their principle of supporting democracy and 'freedom' for others. It's clearly not working out, since the Saudis and other middle-eastern nations are pouring in arms, fighters, and money to support their own little proxy wars over their own sectarian divides. Not to mention the fickle nature of the groups themselves and the lack of loyalty or consistency around what they claim to be for.