Man, I think you did good to buy their drinks. Even if they don't learn something, or calm down, you've done something good that you didn't have to do. I bow down to you, and hope that I get the chance to do something so nice for no good reason, except to do it.
I bet buying them their drinks made you feel a little calmer and better. It probably put it a bit in perspective maybe? They may have just been having a really shitty day, and you buying coffee for them made it that much better.
I applaude you (but there's no clapping emoticon, so
).