They only joined WW2 when the Nazis where pretty much defeated by the rest of the allies and success was guaranteed. Only to invent themselves as the sole winner of the war. During the Cold war they fought hot proxy wars all over the place without any interest in casualties as long as they didn't look weak for the soviets. Even after the Cold war western countries were only lucky that the US didn't invade them for oil or other interests. They brought "freedom" to so many countries by now it became a fucking meme. Sure I'm seeing things a bit narrow and I might be biased but the US is and was a shithole that fucked up everyone around them as long as I can think of. The only reason they could do it is because they would crush you if you tried stopping them or it was useful to you because you weren't the current victim. As you put it so nicely, the convenient bully.