Nothing comes free. In forex business, every things that you face is having its own important. And no one is going to give his work free to you just because of nothing.
It is not the fault of Demo account. We fail because we do not take demo as a serious learning tool. So after demo, we can not able to manage real money.
There may be many reasons for being failed or facing loss for a trader, The one I have in mind is the greed feeilng or having less knowledge of the market.
"At bottom line, learn Forex and be happy with your profits and don’t become too greedy", this is very true for every trader who is going to invest in Forex.