I'm somewhat confused with the phrasing of your question, what do you mean you understand how it benefited the US, but not the US?

Anyway, within the context of the Cold War, the Marshall Plan acted as a facet of containment. Containment as originally outlined had three main goals - restricting the expansion of communism, strengthening the resolve of US allies whilst exploiting fractures within the USSR and international communist movements, and lastly bringing about a shift in the USSR's mindset towards negotiating and coexistence. The Marshall Plan was largely focused at the second of these goals, due to the fairly commonplace belief that communism thrived in poverty, a sentiment expressed perhaps most prominently in Truman's speech to Congress. By providing such massive amounts of funds, the US provided a 'psychological shot', as well as managing to build a level of interconnectedness between the businessmen and politicians of Western Europe that served to solidify the region against the communist threat. It's actual success and motivation is not without debate however, with many revisionist figures such as Kolko pointing out that it can be to some degree painted as economic imperialism and that the direct impact was not all that significant.

Apologies if this answer is not sufficient, any advice or feedback is appreciated.

Sources:

Kennan - Long Telegram

Gaddis - Strategies of Containment

Dennis Merrill, ‘The Truman Doctrine: Containing Communism and Modernity’, Presidential Studies Quarterly, 36(1) (2006), 27-37

Interesting that we're getting a lot of Marshall Plan questions these past few weeks.

Although I'm not as well-versed in the US' policy objectives concerning the Marshall Plan, you might be interested in this answer of mine from last week where I discuss some of the considerations that went into shaping the Marshall Plan. The short answer would have it that with nearly all of Europe suffering from a deep balance of payments deficit with regards to the United States, the American State Department came to believe that Europe was on the brink of economic collapse, or worse — communist revolution. The United States Congress undertook to accelerate European reconstruction and simultaneously make Europe less dependent on US-produced goods through the Marshall Plan.

About a month ago I also wrote how, in the specific case of Italy, reconstruction aid was used as a tool to encourage voters to support the Christian Democracy party. You can read that answer here

Plenty sufficient. Thanks for answering!