about buying P2P

im a newbie and i want to buy crypto using p2p, and i watched tutorials, and i saw that you send the money 1st but the tutorials doesnt really explain why and why i shouldnt be worried about getting scammed aside from saying that pick a verified seller with high completion and many completed transaction, if im sending the money 1st thru a method that binance doesnt really monitored(like Gcahsh if you're filipino), what stopping the seller to from lying that he didnt receive the payment so he wont be giving me the crypto im buying?