The first set of people who quit trading are those who want to make 100% on one setup.....not all set up can you make a 100% on

Risk management doesn't mean a thing to them, so they go all in at once, take multiple losses, and can't go on anymore. The amount of pain proper risk management and money management will save you,words can't explain.

The second set are the ones that learned from babypips, demo trade for a while, in as much as demo trading is good, nothing beats testing the waters with real funds(it's advisable you start with something that's easy to let go if you loose)

 fund their accounts thinking they already understood how to trade. Demo trading won't give you that real money experience (which is the fear of loosing your money,the excitement of winning or the palpitation of your heart when a trade isn't going your way). The whole experience,it's best you start with little capital that you can accept to loose without bulging.

Lose all their funds then give up,then probably pay someone wasting more funds while looking for the holy grill to trading,it doesn't work that way.