All three factors played a role. Mussolini, ironically, was widely respected both inside and outside Italy, especially during the 1920s. Today we think of him as a joke, but he impressed many serious thinkers of the day. Hitler saw Mussolini as a kind of model, although ironically Hitler would soon become by far the more powerful figure of the two.
Mussolini rose to power before Hitler, so he couldn't really look to him as an example. All of the dictators of the 1930s rose to power through a mix of ruthlessness, pragmatism, talent, and luck. Mussolini was able to do so through street politics (the Black shirts) and alliance with capitalists and the Catholic church. Obviously, the situation was right- Italy had indeed emerged on the winning side, but their secret treaty with the Allies that encouraged them to join the war on the Allied side was not honored, and this contributed to a general sense of disillusionment that was intensified by the economic frustrations of post war Europe.
Mussolini was charismatic and a strong visionary, despite the fact that he seemed to some to be taking his cues from Hitler and not thinking on his own. It was a tumultuous time and part of his success was in taking advantage of that, as Hitler and Stalin did.
Mussolini was not the buffoon that he is sometimes portrayed as. He was respected within the Socialist ranks and slowly rose to power over a time period that began well before World War I. His desire for power was obvious, however, and he often flip-flopped policies for his own benefit. He was originally anti-war, and even left Italy to avoid military service, but he later enlisted. An avowed atheist who reportedly dared God to strike him dead, Mussolini found religion shortly before his death.
Obviously, Mussolini must have had some abilities. But there is more to his rise than that. The chaos that arose after WWI certainly helped him come to power. The question is, was the chaos "good fortune" or "national political incapacity?" I'm not sure there's any way to tell. Again, I would think it would have to be both. I might lean towards the latter because Italy was on the winning side in WWI and still ended up with chaos.