Of course Mossadegh actually WAS a socialist, who collectivized farms and land. I don't know what would have happened if we had just left it alone, but I suspect after enough time, Iran would have ended up in the Soviet camp. But does that alone justify overturning a government that was not by itself even a potential military threat?
Does access to a critical resource justify action of this kind? That's a question that isn't as simple to answer as it sounds.
I don't know how history would have turned out if the United States had not adopted its Cold War policy of holding its nose and allying itself with dictators and thugs around the world to keep the Soviet influence out.
God knows plenty of thugs made a career out of playing the USSR and the US off against each other for cash and goodies.
On the other hand, if we had taken a high-ground, "hands-off" policy toward the Middle East, SE Asia, Central America, and other places during the Cold War, I'm not sure how the situation would have improved with the Soviets sitting on the oil supplies and other resources.
When I did my analysis of the potential of asteroid mining some years back (I thought I had posted this once here, but I can't find it now), I had to compare the asteroid resources with Earth supplies. At that time, I found out that a number of critical resources, particularly strategic metals, came from an extremely limited number of nations.
From this source:
...For example, 99% of our planet's known crustal reserves of the platinum metals are located in southern Africa or in the Soviet Union. These same areas contain 98% of the world's manganese ore, 97% of the vanadium, and 96% of the chromium. When we make steel, we use manganese from the Republic of South Africa and Gabon, and chromium from South Africa and the USSR. High-performance jet engines are made of alloys containing cobalt from Zaire. A wide range of industrial catalysts and corrosion-resistant coatings are made from platinum-group elements, which also are supplied mainly by South Africa and the USSR. For each of these vitally important resources we are far more dependent on the Soviet Union and South Africa then we are upon OPEC for petroleum.
Found similar results for things like gold, industrial diamonds, and other resources.
Small wonder we spent a lot of effort trying to keep the communists out of Africa, and why the Soviets tried so hard to gain a foothold there.
We fought the first Gulf War not just to free Kuwait, but to make sure that a hostile nation did not gain a stranglehold on our oil supplies. This was no secret at the time.
Meanwhile, the U.S. enthusiastically destroyed its own nuclear industry, and won't go after new oil on its own soil. Go figure.