Now that's a pretty good argument for NOT going in the first place, don't you think?
If this were a Military argument only, I would agree. But this is also about America’s word. The Budapest Memorandum stripped Ukraine of it’s ability to defend itself under the promise of protection by the UK, the US, and some minor other players. Never again could we calm a hotspot in the world by negotiation. Do you want to necessitate the use of Armed force in all future conflicts that have American interest at stake? If America’s word is worthless, it only leaves force (blood shed) as the future leverage. A good reason to keep our word, wouldn’t you agree?