You have absolutely accurately established what defines the game as "gambling" - it is the influence of luck. It is the factor that allows any beginner to hope that he can win with the first bet in the casino, or in the first match in poker. How many times have I seen the showdown, and when the professionals with a high probability of winning this probability did not work. It turns out that this hope for a wild win attracts people both to the casino and to poker. After all, as we know - beginners are lucky, and it turns out that for them luck is an ally of the game. And when they get a win, they think that it is forever.
Unfortunately for those newbie players even if they can beat a professional once or twice, they have no way to do this consistently and the professional will recover all the money they lost if they keep playing, since poker despite being a gambling game, it is also a game of skill, so it is very common for a newbie gambler to get overconfident about their win and think they can beat anyone, only to find out later they were wrong on their assessment and suffer terrible losses because of it.
Those newbie players still difficult to beat professional players because they have a big difference in skills and other things. Newbie players don't have to think for more to wins the games and just enjoy the game. A newbie player can not expects to have their luck too often because that will not happens as their luck can go anytime. They must realizes that playing poker games requires more skills to beat the opponent. If they don't want to learn more, they will hard to win and will lose even from the same newbie players. And yes, when they win from any poker players, their confidence will increase, making them overconfident and saying that their skills now increase. That will make them not realize the opponent's skill and make mistakes.