If the one time they picked the right side to fight on was an 'intervention' then all the other 'interventions' in Vietnam, Korea, Iraq, Afghanistan, etc. are definitely the right choices, too
This dude punched me in the face, and that's when I decided to intervene...
And what was Germany going to do about it? Send some u-boats over the Atlantic to sink a few ships on our east coast? Frankly, the US could have cooled its heels and done nothing about it. The Atlantic is a pretty non-trivial barrier, and this was before anyone had the heavy lifter aircraft we use today to move lots of troops quickly. More than that, while the US had established supply chains and production lines for building cargo ships fast (we'd been sending cargo ships to England, and the strategy that beat the u-boats was just literally sending more ships than they could sink), which was how we were able to invade and have logistics to support the invasion. Germany didn't have that production capacity spun up, and was broadly successful at having land-based logistics chains, but didn't have much naval logistics to speak of by then. They couldn't even make it across the English channel and essentially turned to siege tactics against England. There was practically a 0% chance Germany would have been able to do much more than the occasional bombing run or sinking some ships. Japan was a much more realistic threat based on their existing military infrastructure, and they, indeed, did manage a brief and kinda sad invasion of US soil (spoiler alert: the Aleutian archipelago in Alaska). Basically, the leadership in the US had been looking for an excuse to get into the European front for a while, and Japan (and Germany's inevitable declaration afterward) finally gave them what they were looking for.