Was going to buy a 1500$ pc from Costco but everyone says to make my own pc

I hear from everywhere that I’ll get my moneys worth making my own pc but I have no idea how to, and don’t know how long it’ll take. I wanna start this process by at least knowing what parts I should get. I want a pc that can play high graphics on modded cyberpunk and monster hunter and new games coming in the future. So I want to see the best computer I can buy with that amount of money or at least have a pc with the best graphics card I can get.