Rely in pure luck will give us 5% chance of winning that's why there are a lot of online games that's popping out with games that no need for us to analyze and gives big amount of jackpot price to attract players, the owners of the website are pretty sure that they will earn big money with that kind of game.
There's is no specific percentage of winning when you just rely on luck, but one thing is sure is that your chances of winning is pretty low.
Games like poker and sports betting needs luck but you cannot use your luck all the time because you don't own it, however if you are good in analysis it will help your improve your strategy and could deliver a win for you.