Do I think that "Luck" is a cosmic force in the universe that one can measure and quantify? Or some sort of mystical force affecting the outcome of my actions?
No.
Do I think "Luck" is a thing all the same?
Yes.
Now, that may be confusing. "Salty, how can Luck not exist and still exist?" I hear you typing into your keyboard at this very moment. (Yes, I can hear you typing. Don't make it weird.)
Well, I don't think Luck is a thing that one has a quantity of or anything like that. Merely, sometimes something happens through no fault or virtue of your own. Rolling a dice is about a random as you can get, but sometimes you "get lucky" with a roll. And other times, you have no luck with a roll and constantly get 1's practically giving you no progress (think board games).
Anyone who has every played a TCG is aware of a certain level of "luck" in the game. Yes, there are things that factor into TCGs. How well you build your deck, your understanding of the rules, knowing how to play your cards for maximum effect, and such. But the "Luck of the Draw" and even how your cards play against your opponents (presumably) random cards are also factors. I've won games because of a single "lucky" draw. And lost games because I couldn't get the cards I needed, or play the ones I had, due to bad "luck". Luck is less a thing and more about playing the odds in this context, though, but luck is a simpler concept.
Other than that, I'm sure we've all avoided injury due to sheer luck. Or were "lucky" to find a rare movie or game at a store. Or just had "bad luck" that your car broke down at this moment that you really needed it.
That's my thoughts on "luck" at least.