"With great power comes great responsibility."

In Spider-Man's origin story one of the first things that happens after he gains his powers is that he tries to make some money as a masked wrestler. A guy robs the box office at the wrestling venue and Spider-Man lets the guy escape because it's none of his business. The same robber later shoots and kills Spider-Man's uncle, from which Spider-Man takes the lesson expressed in the above quotation. The same lesson then colors a large fraction of the character's storylines forever after.