Demo can not make you well experienced. No matter how much profit you make with demo. The real test begins when you start to trade with real money. When you trade with real money you get emotionally attached to it. When we are attached to anything, we tend to make mistakes. Demo can only help you to know the trading platform and test your strategy.
There are a couple of points which need to be taken care of when you are trading on demo.
1. Demo Helps you to practice basics.
2. Demo lets your learn without the fear of losing
3. Execution time in demo is much better in comparison to live (be it any broker, the execution time in live and demo will always vary.)
If you trade on demo with the above mentioned points in your mind, you will realize that one can clearly not call themselves a good trader and gain 100% confidence on live trading.
Firstly, in the live account your capital is always at risk so you would need to be very careful and place trades after proper analysis as their is hardly any scope for luck (which we generally get on demo when we just randomly place any trade :P)
Secondly, you might not get the best or instant price while live trading, the execution time might overlook your entry price and chop your profits.
Thus, its a fact that demo cannot make you a pro but it can surely help you to start to become a pro.
The more your practice, the more you learn.