Luck doesn't play a factor in chess, at all. Life and human error play a factor when it comes to things outside chess. If your opponent gets struck by a meteor during a chess game, that could be considered 'luck'. If your opponent, misclicks, that's Human error. if your opponent miscalculates because their mind is wandering, that's human error. There is zero luck in chess. It's human nature that gets us.
Is Luck a factor in chess ?

Strictly speaking, chess as a game is as far removed from the games of chance as is possible. I can see that problems, studies, correspondence chess are purely non chance. But when it comes to practical play, which in my view is more of a fight than anything else and thus can cause players to experience emotions associated with fighting, then luck can creep in in various forms. Of course the spectators will never know, only the player(s) involved. Who knows,maybe Botvinnik for example was lucky to retain his title twice in 1951 and 1954 vs Bronstein and Smyslov. I mean the history of chess would be different had Bronstein avoided defeat in the 23d game of the match. But I can also see Capa's point, "The good player is always lucky."

You are forgetting that some of them were caught cheating when there was already too late, and it's not that their opponents were less skilled. Directives from Heaven?

Like in many sports, activities, competitions, etc., there is always luck involved. As skill increases in any endeavor, not just chess, luck diminishes quite significantly. For example, luck in a game between scholastic players is going to differ greatly from the amount of luck in a game between grandmasters.
Well, what constitutes luck in chess? A lucky move generally arises in chess if:
- One makes a move that is better than intended
- One arbitrarily makes a chess move with no logical reasoning behind it
- An opportunity suddenly arises that wasn't available on the previous move
- One player is playing below their skill level
That being said, skill is most prevalent in chess as luck for one player occurs from a lack of skill from the other player. Because of this, one may argue that there is no luck in chess. It may come down to how one defines luck.
How can there not be any luck in chess? Topalov won on time in a lost position when his opponent missed how the time control worked. Ivanchuk gave his opponent a draw out of courtesy in a winning position. Azmaiparashvili was allowed to retract a losing move and won. The arbiters didn’t see Kasparov putting his knight down against Polgar. Fischer made a fingerfehler and lost. Radjabov dropped the queen on the floor in time trouble. This type of things do not happen equally often for or against everyone, but are a combination of skill and luck in many cases.
One could of course make many less obvious examples. Your opponent couldn’t sleep all night because of a loud party at the neighbours. He thinks about a quarrel he had the same day with his dad. His wife told him she wants a divorce. His son was just diagnosed with an illness. His daughter had nightmares and kept him awake. He just got a fever. There are many reasons players perform below their usual level in a game. I recall Steffi Graf a few years later commenting on her winning a final 6-0 6-0, with approximately ”my opponent had the worst pains of anyone on the tour when she had her days, and the final was at the worst possible time for her”.

a lot of gambit-openings have been created in the last few decades but is it possible to create a brand new opening, not a gambit, based almost soley on concepts rather than tactics?

I think some people get confused on this because it's often said that chess is not a "game of chance". There is no dice roll or RNG, so in many senses of the word "luck", there is no luck in chess.
But not all senses of the word.
Until the endgame, no player can evaluate all future moves, and luck comes in in terms of the unevaluated space. If I look N moves ahead in a particular line and decide it's good, maybe my opponent has a combination after that that can turn the tables? Or maybe something that I've done in this line happens to prevent my opponent from playing another line that I didn't even see. If none of this were possible then there would be no point playing the game; the better player could just decide his/her whole game right from the start, and would never be surprised or need to replan -- clearly this is not the case.
However, granted, luck is a smaller factor than in many other games; luck is rarely the cause of major upsets.

"luck is the residue of design." if an opponent says to me "you're just luck your bishop [or whatever] was where it was or you would have lost."
naw, the b would up on the square it was when it did was becaause i have a good enough grasp of the game to set my pieces up well, and continue to find good squares for them, even if i don't know, at the time, exactly what specific function they might serve in the future.

Yep! Luck is a great partner!!! Why would anyone not want by their side!? ...don't take my word for it! Take Anish Giri's!
https://www.youtube.com/watch?v=RjC7nSupOJ8
https://www.youtube.com/watch?v=l1rPyeWeMLM

A lot of people here are choosing very convoluted examples of luck, such as opponent missing time control, having a bad sleep etc but what about the most practical example of luck which is when players fail to calculate a given line accurately/miss several variations but still end up choosing the right move? What if faced with a defensive task you have to chose between Kh8 and Kf8, and with no idea which is best you guess and pick the winning line over the losing line?
I myself have being benefitted and lost games many times from positions I was not sure how to evaluate. I think there is a luck element in Chess that you can enter into the unknown but still come out on top.
I just read for N time someone types there is no luck in chess only good moves or smth and i wanted to see what other people think and i am right. There is definetely luck in chess. A lof of luck actually at amateur level specially in bullet and blitz. And that is what most people play. The game/position often goes from white is totally winning to black is totally winning etc. lets say you are attacking and you calculate checkmate. You are excited happy and quickly you make the sac. Few moves later you see that you missed something and king can escape safety, thats pure blunder by you and lack of skills, by then one move later you spot another move that you did not saw before which still wins .. now thats luck.