I myself believe that in gambling it is luck that determines the victory obtained by the gambler, it is luck that gives victory, not our efforts, even if we use an accurate strategy, if there is no luck then it seems that there will be no victory that can be obtained. With the story you told, your friend won, maybe because at that time your friend really had luck. Or you can ask him why he was able to win, whether he gambled using certain tricks or patterns. However, if you really use patterns and strategies, in my opinion it still boils down to luck.
I myself have experienced it, where I, who have been gambling for a long time, have never gotten a big win called a jackpot, even though I have used patterns and strategies that I believe can get a jackpot, it can't give me a win, whereas with my brother who doesn't know anything... what about gambling, where he only gambled once because he wanted to satisfy his curiosity, in the end he made a deposit of money and gambled carelessly without using certain patterns and tricks or strategies, he was able to win, I myself was surprised but it was true maybe this is what is called luck. Also last night, I saw that there was only enough remaining balance to do one spin, and I did it. But miraculously I was able to get a pretty big win. Therefore, I myself believe that luck is what gives you victory in gambling.
Yes, luck plays a big role in gambling but then you need to have good experience in what you're doing, before luck comes it. According to the Op's story if you noticed, the lucky guy which happens to be his friend was telling him to allow him focus and concentrate on his game, that's to tell you that good strategies, focus and concentration also matters as well.
But I think when it comes to jackpot in casino games it's more of luck than good skills, cause there are many individuals that are very good at gambling but are yet to win a jackpot while there are others who just started gambling but would be lucky enough to win a jackpot but it's very rare because in a day the number of people that wins the jackpot are less compared to those who doesn't.
In terms of gambling, I think luck plays a big role in determining victory. Now, for example, there are people who gamble continuously without stopping, so it could be said that they gamble in pursuit of winning, but they don't realize that what they are doing will only make them lose. just money, because even though they gamble continuously, they themselves don't have a portion of luck so I don't think there will be any winnings to be had.
In my opinion, small wins or big wins in gambling depend on luck, with the existing facts about gambling, winnings that are difficult to obtain cannot be obtained even with the skills you have. Indeed, there is some gambling that does require skill, but in my opinion, that doesn't change the portion of luck that exists.