I don't think beginners luck is true in that beginners win more when they first start playing but I do think beginners will win more often in tricky situations (Think poker with someone bluffing really well but a noob not realising and calling an all in) because they don't play by in a predictable or standard way.
Gambling is not a matter of luck, beginner or professional, all have same chance to winning and losing. If there are any beginners who wins it is probably one of the attraction for many more in gambling. If you don't know gambling I recommend to never gamble. Save your money to investments, savings or buying bitcoin.