Both skills and luck really matters, because sometimes even though you have the skills to bluff and have good strategy, if there's no luck on the cards then you'll still lose.
Even you practive everyday and having more strategies if luck is not there then it's useless. Think about the poker game, yes you can bluff but you can't win without luck on the cards.
I don't think luck is the right term, maybe it is but I like to call it "your turn" or "coincidence", it is more realistic. Playing dice, poker, or sports gambling have their own pattern, yes you heard it right, they do have a pattern that randomly changes every time, if you guess the next pattern in the next roll or what next card will be given to you, then you could assure yourself that you could win always,
but the problem is that if the gambling sites notices you are winning too much, they are giving you trouble withdrawing your money so you don't have a choice but to use it on gambling and lost it all, that is why every profits should be withdraw as much as possible to avoid this scenario.