I was thinking about your point that luck includes emotion, and while I don't completely agree with it, I understand where you're coming from with it.
I think a lot of it is because the concept of luck is something we understand at a young age. Since lots of things seemingly happen out of chance (or, at least, it seems that way when a human isn't in complete control of a situation), it's an easy concept to get. Given that + the stakes when gambling, it's easy to associate emotion with it.
Since the concept of "luck" is a lot more natural than "short term variance", it seems a lot more natural to call it "luck", even though it's referring to similar things.
Luck is also a concept that also isn't always easily quantifiable. It is, in gambling, because it's easy to know the house edge, variance, and all the other stats that go along with a particular game. Thus, it seems more mysterious when used in everyday life, as all the factors aren't known.
28) Personal ethics go out the window when there is cash on the line.