In real life, no one open shop by playing monopoly first.
Or being the best in monopoly doesn't mean success with real business.
Forex is a business, so why treat it differently with others?
You just do it with real money. Gain experiences. Learn, do your homeworks, follow real traders, and then start from small. Losing is part of the game. You won't get that feeling from demo account.
Demo account is only for backtesting NEW strategy, manual or automatic.