Rightly said, I also believe that if a trader gets losses, then he should learn to find ways to avoid them in future instead of doubting their knowledge and trading skills.
There are many reasons to fail in Forex trading but according to me not having a trading strategy definitely adds more risk to trader's trading if they are having hard time defining their target and goal.
Practising on demo accounts makes you aware of the platform, market and helps in learning to identify the risks. For beginners, it is the most beneficial way to enhance their knowledge and get prepared for the live trading.
I believe that practising on a demo account is a great way to gain Forex knowledge, it helps you in making familiarity with the market as well as make you aware of the platform. But the real experience comes out after doing live trading.
Firstly Sit back and relax, redo your strategy, consider risk management and other areas where you’re doing wrong and further analyse the market thoroughly before making future trades.
I think you lacked patience, in the greed of getting quick bucks, you have wasted all your money. You must realise that you need to wait, work on your discipline. Going against the market will give you nothing except loss.