As for who will make you pay: the future. That's how it's always been.
Remeber how 9/11 was just a bunch of guys in a tent far away being pissed off at the USA and it caused you a national trauma that has pretty much set the country on a path of self destruction. Make no mistake: Bin Laden won the war, even if he got killed. And for peanuts. Right now the same is happening with Russia and the USA still has not learned its lesson: morality of action is important because otherwise there will be a reaction even if you can't image that the bill will be presented at some point.
As for my own country: we got stupendously lucky given all of the blood and the crimes this country is built on, not unlike the USA. But at least we refrain from giving the world the finger and pretending we're too big to fail (we're not). It really pays off to realize that the USA is not larger than the rest of the world and if you make enough enemies sooner or later they join up against you.
You actually can. It's actually the standard way.
The rest of what you say is nonsense. The world pretended it was true in the post-WWII liberal world order, but it wasn't true then or now.
No one, directly.
Indirectly, undermining our own credibility when we try to foster a rule-based order that doesn't require constant resort to expensive (in both lives and treasure) applications of hard power, OTOH, will have a cost.
> And is that cost less or more than the cost of hundreds of thousands of opioid deaths?
It doesn't matter, because this campaign won't in any reasonable scenario prevent hundreds of thousands of opioid deaths, it will just add a bunch of deaths from international armed conflict on top of it.
Okay this cost seems worth it.
Just for a second consider Canada bombing a US vessel that they suspect is running drugs.