Let's assume a beginner enters into trading without knowledge and indeed most of them are not equipped with sufficient knowledge. So when they get a big profit from their first trade, then it is a stroke of luck. Why? because they entered the market without sufficient knowledge and without experience too. I think that is felt by some beginners who eventually think trading is easy, but they don't realize that they were just lucky at that time. However, not all beginner traders can feel this, it only happens to a few people. I remember some time ago my friend entered the market for the first time and they immediately felt a loss. So it was indeed because of luck.
Experienced traders also have the chance to have losing trades, despite the fact that they have enough knowledge to understand what they are doing, but there are manipulations in the market and it is not even a matter of luck, although in the case of a beginner, luck may matter more than in the case of an experienced trader. The most important thing is that the trader is successful enough in the long term, so that most of the trades are successful and a few losing trades do not greatly affect their results.