I see it's quite old discussion, but I discovered it just now. May I add my answer to your question?
YES, you can make money with just demo account in Forex. I've personally done that few years ago until I earned money for my live real money trading account. Then I switch trading my real money account.
The story began when I've created a profitable algorithmic and completely automated trading strategy. I call it Daily-F. I was very happy with it, but I had a problem that I did not had any money to fund my account with and use my strategy.
So I was using it on my demo account and started my own trading signals business.
I do not want to include any links to my websites as I do not want to be blocked for spam, but you can google to find my book on Amazon called "How to Start Your Own Forex Signal Service". I tell my story in my book and also explain everything you need to know to start your own INDEPENDENT trading signal service with just your DEMO account.
Long story short, I've been trading my DEMO account where I've made virtual money, but at the same time I've been copying trades to accounts of my clients and in exchange they paid me monthly subscription fee. Basically when my demo account gained profit my clients actually earned real money in their accounts.
I've doubled my demo account in 12 months and by that time already made enough money for my real trading account. Then I've invested my money into trading, applied my trading strategy in my own account and doubled account again in the next 12 months, but this time it was my real money account.
I use Signal Magician software to run such business and constantly create new automated trading strategy using the Trading Strategy Launch Framework that me and my partner created this year.
Hope this helps.